Untitled

<html>
	<head>
		<script type="text/javascript">
			function setBG()
			{
				var img_path = unescape(document.URL.substring(document.URL.indexOf('?img=')+6,document.URL.length));
				document.body.style.backgroundImage="url("+img_path+")";
				document.body.style.backgroundColor="#f3f3f3";
			}
		</script>
	</head>

	<body>
		<h1>CSS Background Image<br /></h1>
		<button type="button" onclick="setBG()">Set background image</button>
	</body>
</html>