I need some help with diet and exercise...?!

I'm 13 years old, I'm about 5' 4'', and I weigh about 160 lbs. This summer, a friend and I are going to be working out, and I wanted some help with diet and exercise stuff. I'd really like to have a flatter stomach, skinnier arms, and smaller thighs. Aaand, if there's any way I could get a bigger butt, that'd be great too. :) I would like some different exercises, warm ups, cool downs, and also some sort of diet plan that would help. Any ideas would be great, so please comment away!