What NFL position should i play?

Hi my name is marc i am 14 and i live in Australia i was asked to join a local GridIron team but i dont know what position to play i love GridIrion/NFL , NFL being a league lol anyways i love the game i support San Deigo though my favourite player is Adrian Peterson. I have been a bit confused in what position to play i am 51 kgs/121pounds about 155cm/61inches/5ft tall and i am medium pace fast. I dont know what position to play. =]