Prueba con esta ,la del pro portal
<html>
<head>
<title>{$mybb->settings['bbname']}</title>
{$headerinclude}
</head>
<body>
{$header}
<table width="100%" cellspacing="0" cellpadding="0" border="0" align="center">
<tr>
<td valign="top" width="{$proportal->settings['leftcolwidth']}" style="padding-right:{$proportal->settings['verticalspace']}px">
{$leftblocks}
</td>
<td valign="top">
<a href="
Link><img src="
URL de la IMAGEN"></a>
{$centerblocks}
</td>
<td valign="top" width="{$proportal->settings['rightcolwidth']}" style="padding-left:{$proportal->settings['verticalspace']}px">
{$rightblocks}
</td>
</tr>
</table>
<table width="100%" cellspacing="0" cellpadding="0" border="0" align="center">
<tr>
<td align="center" width="100%" class="smalltext"><a href="http://www.promybb.com/" target="_blank">Pro Portal 1.0</a> © 2010 <a href="http://atopal.com/" target="_blank">Adnan TOPAL</a></td>
</tr>
</table>
{$footer}
</body>
</html>
Si no te sirve dimelo