May be its helpful for you
you can attach the css file or
write the code as below...
just provide the path where image is located in url('imagepath')..
thanks :)
<pre lang="xml"><head runat="server">
<title></title>
<asp:ContentPlaceHolder id="head" runat="server">
</asp:ContentPlaceHolder>
<style type="text/css">
body
{
background-image:url('abc.jpg')
}
</style>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ContentPlaceHolder id="ContentPlaceHolder1" runat="server">
</asp:ContentPlaceHolder>
</div>
</form>
</body>
</html>