How do I do better on the mile?

I am 12 years old and I got 6:59 on my mile. I really want to get 6:05. But how do I do that I mean I run so much.. fine okay theres this boy in my class and he eats soo much junkfood but is like the top runner and pacer in my school and he is super skinny! and im in 2nd or 3rd place out of my school ( 6th - 7th) everyone takes this as a competition. so what do i do? please helppp! tell me what to eat and wwhat excersises?