function changeBGImage() {
    
    newImage = "url(<%= SkinPath %>btnAboutUs.jpg)";
    document.getElementById('MainImage').style.backgroundImage = newImage;
  }



<!-- Begin
var interval = 6; // delay between rotating images (in seconds)
var random_display = 0; // 0 = no, 1 = yes
interval *= 1000;

var image_index = 0;
image_list = new Array();
image_list[image_index++] = new imageItem("/Portals/2/Skins/splashscreen/fampark.jpg");
image_list[image_index++] = new imageItem("/Portals/2/Skins/splashscreen/fambeach.jpg");
image_list[image_index++] = new imageItem("/Portals/2/Skins/splashscreen/Doctors.jpg");
image_list[image_index++] = new imageItem("/Portals/2/Skins/splashscreen/ladydoc.jpg");
var number_of_image = image_list.length;
function imageItem(image_location) {
this.image_item = new Image();
this.image_item.src = image_location;
}
function get_ImageItemLocation(imageObj) {
return(imageObj.image_item.src)
}
function generate(x, y) {
var range = y - x + 1;
return Math.floor(Math.random() * range) + x;
}
function getNextImage() {
    if (random_display) {
        image_index = generate(0, number_of_image-1);
    }
    else {
        image_index = (image_index+1) % number_of_image;
    }
    var new_image = get_ImageItemLocation(image_list[image_index]);    
    return(new_image);
}
function rotateImage(place) {
    var new_image = getNextImage();
    //document[place].src = new_image;    
    new_image = "url("+new_image+")"   
    document.getElementById(place).style.backgroundImage = new_image;  
    //alert(new_image);
    var recur_call = "rotateImage('"+place+"')";
    setTimeout(recur_call, interval);
}
//  End -->