I'm trying to make it so that people can advertise on my forum. It is guest friendly, so I need to be able to allow guests to post external links to their sites. How can I do this? I tried to go through the permissions of the forums, but there isn't an option specific to posting links that I know of.

My site is http://wanteddeadoralive.forumotion.com/.

Administration Panel => General => Forum => Security => Unauthorize guests to post external links

Also check other options there that you'll need to adjust for guests on your forum.