how to fix a background in a page in css

body
{
margin-left:0px;
margin-right:0px;
margin-top:0px;
margin-bottom:0px;
background-attachment:fixed;
background-image:url(422483_188897564547740_100002824940270_270455_1252668894_n.jpg);
background-repeat:no-repeat;
background-position:center;
}