I do not know what position i should be for football any advice?

Im 13 years old and im going to start football this year for the first time but i dont know what position. I do track and field but i usually do 50yd,100yd,200yd, 4 by 100, 4 by 200. I usually get 1st places on those events. I can tackle,juke, and i play with the high schoolers. Im in 7th grade by the way. my height is 5'6 and i way about 113 pounds. So any advice? Thanks