How do i lose the rolls and extra skin to get a flat stomach with visible 6 pac?

[Yo Boy!]

I want to lose some fat. How can i lose it without haveing extra skin. I dont want belly rolls i just want a flat stomach and a visible six pac. My six pac shows wen i lay down but when i sit up its all like fat. I only have one roll wen i sit up but i dont want any. I'm 103 pounds and i want to be 100 or 99 pounds wat do i do to get a flat stomach and no extra skin or rolls Help! Btw im 13 year old