Start with this routine:
Day 1: Shoulders, Biceps, triceps
Day 2: Legs
Day3: Chest
Day 4: Back, abs
Simple. Effective. You're only 16 bro. you dont want to start doing anythng heavy. Just stick with the simple exercises, though I'm not sure you know what that means.
My advice is do some research or get a training partner to show you the exercises in the gym before you do them.