You have already got some excellent guidance. You need to eat more to gain, well theoretically you could move less but that is a shitty option for an athlete, and weights are the most proven path to adding muscle.
I will just give some general advice. At your age I would just try to get in great shape cardio wise and get stronger. The body comp changes should take care of themselves to a certain extent. I would not worry too much about â??bulkingâ?? or â??cuttingâ?? in the traditional sense. At your age you should still put on muscle easy, which is great.
If you can keep the "I consider myself a beginner" mindset throughout training and education you will go far. I think maybe one of the keys to that is to search out groups/scenarios where you really are a beginner relative to everyone else. In other words, once you are the toughest guy on the mat, smartest kid in class, etc., go find another mat, or class, or what have you. I did this when I was younger and I think I am the better for it. I need to do more of it now.
You have experience wrestling, I am going to assume you are wrestling for your school, so in-season strength/conditioning and practice schedules are probably dictated to you. Off-season you need to get access to a weight room. A gym with free weights, squat racks, and that allows lifting from the floor (deadlift, power clean, etc.) would be preferred, especially for a wrestler. For someone new to weight training I really like Starting Strength by Rippetoe, both the book and DVD.
It is a designed to be a beginnerâ??s program and it is how I wish I would have started out. Regardless of what training program you do, learn how to perform the lifts correctly and safely. I really like Joe Defrancoâ??s "West Side for Skinny Bastards" program for athletes, but it assumes you can perform the exercises in Starting Strength safely. Of course DeFranco is a master of teaching lifts as well, so at his gym it may be perfect.
Everyone thinks the basic barbell exercises (squat, deadlift, bench press, overhead press) until they get stronger, pile on weight, and get hurt. One reason I recommend Starting Strength is that it gives you a lot of practice with the movements before you get so strong that you either tear yourself up with bad form or have to knock the weight back down and struggle with doing it correctly. I have done both. Donâ??t be me.
Some would say you donâ??t have to bench for fighting, grappling, wrestling. They are right, but I would not have listened at 17, or 27, so learn how to do it correctly. You need to keep your shoulder blades pinched together and down or you may wind up like one of the guys in this thread: http://tnation.T-Nation.com/free_online_forum/sports_boxing_fighting_mma_combat/531_7
Here are some links to articles or things I mentioned:
Here is Dave Tate in a T-Nation video explaining bench form
On Mark Rippetoe and Starting Strength
Hope some of this helped, or at least didn't feel like a waste of time. If you have any questions feel free to ask. I have a long ,early to late, day of work ahead of me, but hopefully we can hear from some others who have been in your shoes and may be able to give better, less general advice than I can.