Hi! Can someone please help me?

I am 13 years old,around 5'3 and 120lbs. I decided to take charge after i saw my self getting "fat". There are kids in my grade who are about 120-130lbs and they are totally skinny (flat stomach etc). Wheras i'm the opposite.

Recently my dad bought me 10lb and 20lb weights. Can someone please tell me how much I should be lifting and for how much? Do I have to run/walk/sprint and for how much? How much meals and calorie intake should I be eating?

All comments appreciated. Please help XD :-P