Just wanted to add-
1)get a workout partner to keep you motivated. Someone around your size and strength is good, and at least an EQUAL amount of motivation is vital.
2)Get someone to lead you through a basic exercise program, at least once. Most of us would agree here that most beginners try to make things much more complicated than they really need to be. Read the articles “Dawg School” in T-Mag. will help a lot.
You are probably still in a growth period, so just by altering your diet and working out properly, I guarantee you will see good results!
Get back to us in a few months with your progress. Good luck, SRS.