div#title{font-size:small;  color:##99FFFF;background:#0066CC

url("http://gotoknow.org/file/thuraphan/watphum.jpg")

 no-repeat   center; height:250px;}div#page-wrapper { background-image: none; }

div#subtitle { background-image: none; }

<style>body{background-image:url("http://gotoknow.org/file/thuraphan/watphum.jpg");}</style>

จะตามมาดูนะ