Please give some more information such as:
Weight
Height
How many push ups/pulls ups/chin ups you can do (or something to see how strong you are)

Start reading though that is key to figuring out what you will need.

RossTraining - Bridging The Gap Between Ordinary and Extraordinary
Jump higher, run faster, and perform better - enhance athletic ability
Build Muscle & Lose Fat through Strength Training | StrongLifts.com

All are great sources of information.

Basic tips though:
Get stronger weight training is effective and safe. (Do you have access to weight?) If not then do Ross style training which is equally as effective.

Work on technique and shot
Work on boxing out, driving to the hoop, passing, etc.
Gain or lose weight
Start eating healthier

I'll be abled to help you more once you give more information though