[Triky]

AdminCp -> Styles & Templates -> Edit your style -> Search for header template.

After this code:

<!-- logo -->
<a name="top"></a>
<table border="0" width="$stylevar[outertablewidth]" cellpadding="0" cellspacing="0" align="center">
<tr>
    <td align="$stylevar[left]"><a href="$vboptions[forumhome].php$session[sessionurl_q]"><img src="$stylevar[titleimage]" border="0" alt="$vboptions[bbtitle]" /></a></td>
    <td align="$stylevar[right]">
        &nbsp;
    </td>
</tr>
</table>
<!-- /logo -->

Add:

<table cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" class="tborder" align="center">
<tr>
<td class="tcat" style="text-align: center;">
<a href="yourlink.php" target="_blank"><img src="yourimagelink.gif" border="0" style="vertical-align: middle;" /></a>
</td>
</tr>
</table>

Changing the red code by yours [Create your own vBulletin tables].