The key is to eat. Eat tonnes of good of food. As much as you love it, let's face it, it's not good for you. No junk foods, keep it healthy otherwise you will feel like shit and you will have a hard time taking a dump. If you're trying to gain weight with a shitty diet, it will cause constipation due to fatty junk foods and if your not eating enough fiber.
You'll have to do cardio in the morning. Why? It will help keep up your appetite so that you can eat all day long. EAT EAT EAT EAT JUST FUCKING EATTTTTT until you feel like throwing up. Also, eat or drink a lot of dairy or whatever before you go to bed.
lol, i feel like im eating a lot but im still gaining like 5 lbs a semester (roughly 5 months). #twink life is hard
This is terrible advice. Do this:
Add protein to your diet, lots of it. The easiest way is with a high grade protein powder (minimum 30 grams/scoop with no more than 100 calories). You can also eat a lot of lean meat but that has a tendency to be difficult, expensive, and a hassle. Some think it is important to do this within a half hour of finishing your workout. I do. Some say it is more the total protein per 24 hour period.
Use the gym properly. Go five days/week and each day pick a body part like arms, shoulders, back, legs, core and focus on only that for that day. Do 4-5 different exercises focusing on that part and do three sets of 10 reps for each. Try to raise the weight a bit whenever you can but at least every 3-4 weeks (not ever time you go). There are more sophisticated exercise plans but this is an easy, good way to get familiar with the gym and get into a routine.
Eat healthy. Don't focus on quantity, just eat healthy, non-processed food. Lots of fruits and veggies and healthy protein. Especially fish (not fried). Make it a diet that you can live with forever and give yourself a couple of times each week when you "cheat" on your diet but even then, don't eat a whole pizza or something stupid.
Focus less on cardio exercise or cardio activities. Unless you just love them. Think of gaining muscle while keeping the fat down. A lot of guys intimidated by the gym spend all their time on cardio equipment and never really get into a weight lifting routine. Don't do that.
If you don't shower at the gym and don't do a lot of cardio at the gym you should be in and out in about an hour or even less.
You will build muscle. You still may still be a bit of a twink but you'll be a muscular one and the day will come when you outgrow the twink phase and what you'll be is a lean, muscular guy.