function Changeimg()
{
	var arrUrl = new Array("top_img/1.jpg",
			"top_img/2.jpg",
			"top_img/3.jpg",
			"top_img/4.jpg",
			"top_img/5.jpg",
			"top_img/6.jpg",
			"top_img/7.jpg",
			"top_img/8.jpg",
			"top_img/9.jpg",
			"top_img/10.jpg"
			)
	nTemp = Math.round(Math.random()*(arrUrl.length-1));
	strHtml = "url("+arrUrl[nTemp]+")";
	document.getElementById("tbimg").style.background = strHtml;
}