Probably the easiest way would be to create a new template and then name it banner.tpl.
Code:
{* $Id: banner.tpl *}
{capture name=menu}
Your text here
<hr />
<img src="{$ImagesDir}/banner.gif" alt="Banner" />
{/capture}
{ include file="menu.tpl"
dingbats="dingbats_categorie.gif" menu_title="Banner"
menu_content= $smarty.capture.menu }
Put {include file="banner.tpl" } wherever you want it to appear.