Hey Russell,
Typically you create a new table with the left, center and right images laid out as cells with width and height settings. It is difficult to give you an example as it depends on the size of your images, etc. and whether you are going fixed or liquid with the style.
This is an example from the forumhome template...maybe it will help:
PHP Code:
<!-- top category table setup -->
<table width="100%" style="background-image:url($stylevar[imgdir_misc]/top_right1.gif)" border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="63" height="31" align="left" valign="top"><img src="$stylevar[imgdir_misc]/top_left.gif" width="26" height="31" alt=""></td>
<td width="50%" class="tcat" style="background-image:url($stylevar[imgdir_misc]/textbg.gif)" align="left">
<div align="left" class="navtext2">
<b>What's Going On? </b>
<if condition="$show['subforums']"></if></div>
</td>
<td width="50%" height="31" align="left" valign="top"><img src="$stylevar[imgdir_misc]/top_right1.gif" width="77" height="31" alt=""></td>
<td width="206" height="31" align="right" valign="top"><img src="$stylevar[imgdir_misc]/top_right.gif" width="206" height="31" alt=""></td>
</tr>
</table>
<!-- END top category table setup -->