Как изменить фон сайта?

<script language="JavaScript">
 
// (C) 2003 CodeLifter.com
// Free for all users, but leave in this  header
 
// =======================================
// set the following variables
// =======================================
 
// Set speed (milliseconds)
var speed = 50000
 
// Specify the image files
var Pic = new Array() // don't touch this
// to add more images, just continue
// the pattern, adding to the array below
 
Pic[0] = '/bg/1.jpg'
Pic[1] = '/bg/2.jpg'
Pic[2] = '/bg/3.jpg'
Pic[3] = '/bg/4.jpg'
Pic[4] = '/bg/5.jpg'
Pic[5] = '/bg/6.jpg'
Pic[6] = '/bg/7.jpg'
Pic[7] = '/bg/8.jpg'
Pic[8] = '/bg/9.jpg'
Pic[9] = '/bg/10.jpg'
 
 
	for(var j, x, i = Pic.length; i; j = parseInt(Math.random() * i), x = Pic[--i], Pic = Pic[j], Pic[j] = x);
 
 
// =======================================
// do not edit anything below this line
// =======================================
 
var t
var j = 0
var p = Pic.length
 
var preLoad = new Array()
for (i = 0; i < p; i++){
   preLoad = new Image()
   preLoad.src = Pic
}
 
function runBGSlideShow(){
   if (document.body){
   document.body.background = Pic[j];
   j = j + 1
   if (j > (p-1)) j=0
   t = setTimeout('runBGSlideShow()', speed)
   }
}
 
 
</script>