Code:
<!-- logo -->
<a name="top"></a>
<table border="0" width="100%" cellpadding="0" cellspacing="0" align="center">
<tr>
<td align="center" valign="top"><img src="$stylevar[imgdir_misc]/logo.jpg" border="0" alt=""/></td>
</tr>
</table>
<!-- /logo -->
<!-- content table -->
$spacer_open
$_phpinclude_output
$ad_location[ad_header_end]
Now replace the "logo.jpg" file with a logo that is any size you want. It should appear in the top center.