var img_width = "606";
var img_height = "102";

var ad=new Array()
//insert here your images src
ad[0]='http://www.corinthian.com.ph/images/ads/corinthiancourt.jpg';
ad[1]='http://www.corinthian.com.ph/images/ads/milelong.jpg';
ad[2]='http://www.corinthian.com.ph/images/ads/thegallery.jpg';
ad[3]='http://www.corinthian.com.ph/images/ads/yhx.jpg';

var xy=Math.floor(Math.random()*ad.length);
document.write('<img src="'+ad[xy]+'" width="'+img_width+'" height="'+img_height+'" alt="">');