1.) You need forum software
[indent]phpBB FREE
SMF FREE
Invision Power Board
vBulletin (What this site runs)[/indent]
2.) You need to follow the install document acquired with the forum you chose
3.) Look at their forums and look for tutorials on how to edit certain templates/css files to change the look.
[indent]phpBB I have found is the easiest to edit, since all the .tpl files are basic html. SMF is a lot more robust and you don't need "language" files (or as many).[/indent]