Liljone the guys are heading you in the right direction but just saying to eat really doesnt help much. I'm sure you've had people your whole life telling you to eat more. For most people it is that simple, eat more, gain weight. For a guy like yourself it's still true but not so easy.
I have a friend like you, I think he was about 135 or so at about the same height, but he regularly are 4000 calories a day, high protien, but the guy would eat pizza everyday or whatever he wanted and stayed ripped. At 135, and skinny as shit, he was they type of guy who was still ripped looking with his shirt off, so he had muscle and was pretty strong but just could not gain weight.
Basically the first thing you need to do is count the number of calories you consume right now on a daily basis. Be honest with yourself, if you eat 1200 a day, record that, if it's 5000 a day then record that. There are a ton of apps for phones used to count cals and have common foods/fast foods/etc and you can add your own stuff. But again be honest, dont guess and add a few extra here and there. Most people are amazed to find out they take in a lot less then what they think they do. Do this for a full two weeks, record every day all calories you consume and eat like you normally do, even if it's pop tarts and potato chips.
This will give you an idea of how many calories you consume in average. It's a starting point. If you want to be dedicated then count protien, carbs, fats as well. Like I said there are phone apps or you can google a calorie counter.
You can also use sites to figure out your maintenance calories. This is what you need to maintain your current body weight, just look online. Fitday or something like that. Basically what I would do is take your maintenance cal (and be honest here with activity levels etc), then add 500 cals a day to what you require to maintain. So if it's 1800 maintenance + 500 then you will make sure you get 2300 calories a day. Do this for a couple weeks. In theory you should gain 1 lb a week like this, I know big changes right lol, but it will take time. If you are not seeing any gains, add another 500 a day so you would be at 2800. These are just examples.
I tend to think that a guy like you should eat 3-4 large meals a day as opposed to eating 5-6 smaller meals. Eating smaller meals spread thru the day will keep your metabolism running and you really don't need that. Once you start paying attention, you should be able to find calorie dense foods pretty easily. Also don't try to eat to clean, you are trying to add weight and while you want quality weight you probably aren't going to be someone who gains fat.
You need to lift weights 3-4 days a week, and not hours a day, 45-1 hour is all you need. You need to focus on compound lifts, flat bench, dead lifts (with proper form), and squats. YouTube im sure has a million videos on proper form. Get a training partner. You want to lift heavy (heavy for you) and low reps. The three above are your core exercises. Then add a couple other lifts for the day. Something simple would be :
Monday:
Legs: warm up by walking slow pace on treadmill for 10 minutes, some stretching can be done at home before. Leg presses can be used to warm up if needed. But your main lift is squats, and do them deep, start with a low weight to get a warm up set or two then 2-3 sets of heavy weight at 3-6 reps.
Then you can do a couple sets of leg presses, again high weight/low reps. Front and reverse extensions and a couple sets for calves and you should be done
Tuesday: chest/tri's
Flat bench: 2-3 sets 3-6 reps you can alternate between barbell and dumbbell weekly
Incline bench the same as above, and alternate BB/DB
Then add something like cable/machine/or DB flies.
Dips 3 sets at body weight for as many reps as you can do. If you can do 3 sets of 10 reps easy then use a weight belt and add 10-25-35-45lbs until you are doing 3-6 reps.
I also do Tri'son chest day since you are already working them. Just choose two exercises, pushdowns, skull crushers, kickbacks, close grip bench, or whatever for 2 sets each. These you can stick to low rep or just use it to burn out at the end of training and go up to 10-12 reps, eventually adding weight and less reps.
Wednesday off or back/Bi's
Back :
Deadlifts: this is your core lift for the day. It will work a lot of muscles. Warm up with 2-3 light sets work on form, form is important here. Then 2-3 working heavy sets 3-6 reps.
And you can alternate weeks with rack pulls and from the floor
Then add a couple others, tbar, one arm dumbbell pulls, pull ups (eventually with weight), machine pull downs, etc.
Same day Bi's: maybe 2 exercises. Barbell curls, easy curl, preacher curl, DB curls. You have lots of options. Here you can go with a weight to try for 10 reps, if you get that increase weight, you could super set, drop set, or to failure.
Last day: shoulders/traps
You don't need much since you have already worked these some, but you can do a BB or DB press, over head press, then a couple light sets (15-20lbs) of side lateral and or from lateral raises. Also a rear delt, which I typically use a machine.
Traps I will alternate between BB/DB/machine shrugs. 2 sets 6-8 reps
You can look at programs like 5x5 or 321 or DC, but I'd you pick one, stick to it, don't try to change it. Lift heavy low reps. Then you need lots of rest. You build muscle out of the gym by resting/sleeping and recovering.
Some supplements that will be helpful to you:
Bcaa- Branch chain amino acids 5-10g a day. On's 2200 are good
Eaa's.- essential amino acids good during training, also you can get these and bcaa's as a powder and mix with water to drink during training
Protien- just a shake immediately after training, then a meal about an hour later 50g + protien from the shake. Find one that is good and doesn't make you feel overly full or bloated after. I would use 6-8oz whole milk and 2 scoops powder.
Glutamine- add 5g to protien shake pwo, and another 5-10 g either before training or before bed. It will help with recovery.
Creatine, 5-10g this can be mixed with bcaa/eaa and drink before or during training mixed with water.
For breakfast eat 3-6 eggs, find ways to eat them because it's not much, you can eat them with bread or scrambled with hot sauce. Add 1/2 to 1 cup oats. If you need a quick breakfast: add 1cup oats to bowl, 1/2 cup milk, 1cup plain Greek yogurt, 2 scoops chocolate protien powder. I add the oats, milk, Greek yogurt and mix well and place in fridge at night. In morning add 2 scoops protien and mix well. Eat cold. It's tasty and fast plus lots of protien and complex carbs, some fats.
Then eat a good size lunch, eat about an hour before training with high protien, there are lots of option, 2 cans of albacore tuna with mayonnaise (yea it's basically fat but you want to add weight) with it w/o bread, peanutbutter and jelly, whatever.
Then have your bcaa/eaa/creatineglutamine drink in water during training.
Protien shake pwo (2scoops and 6-8oz whole milk). About an hour later a full meal. I usually have a steak, sweet potatoe or red or yellow baked potatoe, and some veggies. Eat as much as you can.
Then right before bed have a shake; ( I don't really like the idea of so many shakes but if you have trouble eating enough shakes can help). Really I'm only saying a pwo shake and possible pre bed, but also add protien powder to the oats/Greek yogurt if you need a quick breakfast and it taste great.
The pre bed shake: 1 cup oats-blend into a fine powderpowder. Then add 2 scoops protien powder, i prefer chocolate, 2 table spoons peanut butter, 1-2 table spoons EVOO (yes olive oil for fats and calories) you won't taste it, 1 banana, 8 oz whole milk, 10-12 ice cubes. You can add or change banana for others if you want. Blend this until well blended so it's not chunky. If it's too thick, which it shouldn't be, add more ice cubes or a couple oz of milk, ice cubes will be easier.
This shake is at least 1000 cals, and 60-80g protien with complex carbs. Thiswill hold you over during the night and you can drink it down pretty quick.
It's best to have a meal instead of the shake pre bed but if you are tired of eating this will be easier. I know guys who add ice cream to it as well. When bulking, I will make this shake and either drink it if I wake up during the night to piss or will even set my alarm 4 hours into sleeping, drink the shake that's pre made, and go back to sleep.
You will add weight if your body is getting the necessary nutrients and training hard, but don't over train and lots of rest. Get online and get the supplements cheap, dont pay expensive gnc price. Don't pat for weight gainers, my shake is better and cheaper.
Sorry for the long post but I'm just giving you an idea of how to approach things. Keep cardio to a minimum for now. When I was younger and plating hockey, with practice twice a day, conditioning, then weights, it was hard to gain.
Gear won't do much at all if you aren't able to eat what you need to grow. Get use to eating more, more protien, and lifting with core exercises and heavy. Have a partner to help force the last reps until you can get them on your own. Forced reps really help. Eat, train, sleep. These supplements will be all you need. Put some time in like this, add some weight, strength, and strengthen tendons and then look at a cycle. Right now you would likely run gear, gain a few pounds, then lose the majority after because you can't eat enough to maintain the new weight.
If you really want to gain weigh ang get past being skinny you will gave to work for it and not give up. It takes time but you should start to see results in the first couple months. It wouldn't hurt to see your doc and get a physical and blood work including lipids and a hormone panel to see what's going on in you body. Have your thyroid checked. And if you need to add some junk to get the cals then do it. Eat as much good protiens and cals but I'm not opposed to pizza and whatever just to get you going.
Consistency is the key. If you don't stick with it, you are wasting your time. Give it a couple months and I bet you will be happy and won't ever want to go back to that skinny guy again. You could make things easy and get with 3J and hire him to do a bulk diet for you, he has discount codes and affordable packages, its important.
Good luck. I hope I didnt just waste all this space for no reason, take what info I'm giving you and do more research because I'm just throwing out very basic info. 3J can have you gaining weight.