i am 13 years old,5'5 and about 8 stone,and im wondering what psition is best for me,and any tips on playing that position

Well if your slow at running prop,hooker or lock would be good. If your good at tackling and getting the ball back in rucks be flanker or number 8. If you have good passing skills and you can run fast under pressure be a back. BTW im from NZ and i have played rugby for years i know my stuff.