I found my answer.
<?php
$profpic = "bg.jpg";
?>
<html>
<head>
<style type="text/css">
body {
background-image: url('<?php echo $profpic;?>');
}
</style>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Hey</title>
</head>
<body>
</body>
</html>