i have jst started and want 2 get a board

Hey!
my names kate and im 13, i have decided id love to take up surfing, i have only surfed on the foam boards, and would like to get my own propper surfboard, secondhand if posible, and was wondering if anyone could tell me wat the size is ment to be like and where a good place is to get them :?:
Thanx
my names kate and im 13, i have decided id love to take up surfing, i have only surfed on the foam boards, and would like to get my own propper surfboard, secondhand if posible, and was wondering if anyone could tell me wat the size is ment to be like and where a good place is to get them :?:
Thanx