собственно вот эти фоны он меняет из css:
body.inner { background:url(../images/bg_top_red.jpg) 50% 0 no-repeat; }
ul.indexbg { position:absolute; left:0; top:0; width:100%; height:500px; list-style:none; margin:0px; padding:0px; z-index:1;
}
ul.indexbg li{ display:none; position:absolute; left:0; top:0; width:100%; height:570px; }
ul.indexbg li#bg01 { background:#fff url(../images/bg_main_top_red.jpg) 50% 0 no-repeat;}
ul.indexbg li#bg02 { background:#fff url(../images/bg_main_top_black.jpg) 50% 0 no-repeat; }
ul.indexbg li#bg03 { background:#fff url(../images/bg_main_top_blue.jpg) 50% 0 no-repeat; }
ul.indexbg li.active{ display:block; z-index:2; }
ul.indexbg li.active2{ z-index:3; }