Paste the code below to either the custom markup footer for it to appear on all pages or to your actual pages if you only want it on certain pages. Adjust the background image location to your needs.
<style type="text/css">
<!--
.footer{ position: fixed;
bottom: 0px;
left:0px;
width:100%;
}
#footer_content{
width:942px;
height:100px;
margin-left:auto;
margin-right:auto;
background-image:url('http://mydomain.com/images/welcomefooter.png');
}
-->
</style>
<footer class="footer">
<div id="footer_content"></div>
</footer>
