<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head>
<title>XXXX</title>
<meta http-equiv="Content-Type" content="text/html; charset=WINDOWS-1254" />
<style type="text/css">

.altkatman
{
    background-image: url('images/alt.gif');
    background-repeat: no-repeat;
    width: 100%;
    height: 100%;
    position: absolute;    

}
.ustkatman
{
    background-image: url('images/ust.gif');
    background-repeat: no-repeat;
    width: 100%;
    height: 100%;
    position: absolute;

}

    </style>

</head>
<body>
<div class="altkatman" >
<div class="ustkatman" >
</div>
</div>
</body>
</html>
Şu yukardaki kodlara bakarak bişeyler çıkarırsın sanırım .