Top1.gif is set as a background for that cell.
It will tile to fill the whole area. That is why the design is vertically symmetrical.
<TD background="{$ImagesDir}/top1.gif" align=right valign=middle>
If you make a like sized image it will also tile it, so be sure to keep your image able to be "joined at the butts".
If you make a particular sized image that is also fine (be sure to change the width and height properties in the tpl) however you will lose some of your aesthetic appeal when users with different browser resolutions visit your site.
Good Luck!
