water mark or background fixed and content scroll

/* First write this code in stylesheet.css*/
body
{
background-attachment:fixed;
background-image:url("img/Sunset.jpg");
background-repeat:no-repeat;
}

/* now link the stylesheet to the page in Head tag by using*/
link href ="stylesheet.css" type ="text/css" rel="stylesheet" /

/* now write the content in the form tag of page source code*/