To make TouchBB work with your own forum, a single file must be uploaded into your forum directory. There are no other modifications required. If you are not the forum owner, all you have to do is send the forum admin/owner the following informational link:
http://www.messageforums.net/iphoneforumreader.php

If you downloaded TouchBB for use on an existing forum, please add that forum under the Account tab. There you can also create a new TouchBB enabled forum by hitting the [+] button.