Best to learn on a soft top. Easiest to get up on and no pain if you get hit by one.
For your size 7-8 feet is plenty. Once you can ride that...start shopping for a real board. You can find a softie for about 75-100 bucks.
Thanks for all the advice. I just went to a pawn shop and got a 7'6 board. I think it is in pretty good condition. For all the guys posts on here. I am 20 years old, just tiny. and yall are weird. Sorry but you wont be getting a picture of me. I have no idea what the shape of the board is though. I dont think its fun shaped though.