What forum system do they use?

If you don't know what system they use, you can usually find out at the bottom of the screen. A lot of my friends make their own boards so, if that is the case with your friend's board, you might just want to ask him/her.

Edit: Oh yeah. There's usually a link to the system website at the bottom, too. If not a link than try to google the system name for an address. There should be documentation on the site.

Alcides.