I'd recommend to you what i took when i was your age and skinny and that is ''Gainers Fuel'' by twin labs. Each serving is 2,500 calories and BCAA'S protein galore...and for exercising at 17 are you still in high school and is their a weight room there like at my high school. You may want to join the YMCA ( if you have one) and it may be good for you since your 17 you don't need hard core gyms yet..They'll have somebody (trainer) there who can show you the proper way to lift weights........