how do i gain more muscle and have a nutrition plan?

[yournamehere]

i play basketball player and i wouldn't really say i have an athlete's body. i have belly rolls, i'm scrawny as fuuuuu, and my vertical is absolutely horrid for a hooper. I was on my school's freshman A team and just relied on my shooting abilities but i wanna be able to do more then just shoot. Most of the players at my local court are much stronger and bigger then me and can just push me around and score an easy layup if they keep me in the paint, but i wanna change that. i wanna get fit and gain strength that'll help me out when playing. my diet is just indescribable, i eat when i want and whatever i want and it usually consists of fatties and junk foods. i have very little biceps, can barely do 60 pushups nonstop, and bench is at around 135. i'm around 5'8 and weight 148 pounds. i need help! all answers are welcomed! jusst please, keep it mature.
alot of grammatical errors but w/e! and i'm also 15 and a sophomore in highschool.