You want to change the background of the forums that are just links? You'll have to edit the template and add a class to the row and then define the class to have a different background color. ie:
<li id="forum{vb:raw forum.forumid}" class="forumbit_post L2 <vb:if condition="$forum['statusicon'] != 'link'">forumlink</vb:if>">
Then define .forumlink {background

ink;}