MyImages=new Array();
    MyImages[0]='randomImages/hd_img_1.jpg';
    MyImages[1]='randomImages/hd_img_2.jpg';
    MyImages[2]='randomImages/hd_img_3.jpg';
    MyImages[3]='randomImages/hd_img_4.jpg';
	MyImages[4]='randomImages/hd_img_5.jpg';
	MyImages[5]='randomImages/hd_img_6.jpg';

    function newImage()
    {
        document.getElementById("mainImage").setAttribute("src", MyImages[Math.round(Math.random()*5)])
    }