Using CSS to display a background image that will stretch to cover the entire page.
<style type="text/css">
html {
background: url(IMAGEURL) no-repeat center 10% fixed;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(src='@IMAGEURL', sizingMethod='scale');
-ms-filter: "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='@IMAGEURL', sizingMethod='scale')";
}
</style>