Use weight gainer and eat literally everything.
hi d1v3n. what you need to do to gain muscle at your age is to eat loads, get adequate sleep and train EVERY body part. most of it wont go on as fat cuz ur young, all that loads of food will do is feed your muscle. you might also need to invest in a bench and barbell so you can start doing some proper compound exercises. go on the teenbodybuilding website (not sure if im allowed to post links, cuz they got loads of help for people at our age on their forums. get a routine going that includes every body part and do less reps on a heavier weight while maintaning form. aim for about 5 - 7 reps x 4 to 5 sets for each body part, it'll help u grow. nah you wont stop growing at your age that's just a myth.