[likecat]

Start with this:

http://www.forumotion.com/

After you've got an Idea about this you could start with some Tutorials about how to work with a ftp server and filezilla.
After that you could google for "Mybb" , download the forum software and upload + install it.

If you've questions about http://www.forumotion.com/ send me PM.

thank