Morning Jack,
The typical way to had a clickable linked picture is with an anchor tag as follows:
<a href="URL link for check other auctions page"><img alt="" src="url for image button" /></a>
The href is the "http://....." link to your eBay listings page.
The W3schools has some more examples here:
http://www.w3schools.com/tags/tag_a.asp
Danno