I did this in my footer.php of my Kakumei theme.
Find your theme folder. E.g. /forums/bb-templates/YOUR-THEME/footer.php.
Edit footer.php code:
<div id=”footer” role=”contentinfo”>
<p><?php printf(__(‘%1$s is an online discussion site of the YOUR-DOMAIN.com‘), bb_option(‘name’), “http://YOUR-DOMAIN.com”) ?></p>
