you need a host that supports mysql..
also if you wish to go down this route with just a forum, sign up for a free forum (who host it for you) and then buy a domain.. £5 or somting a year.. don't have much you can do though in regards to editing it etc.
if I was you, I'd get a decent host and buy your own domain.. this way you know what your getting and it's what you want.
A few good hosts are bluehost and hostgator.. there cPanel is the best by far imo and supports everything you need.
PM me if you want to know anything else.