//Edit this line to list all of your background images 
var backgroundSrcs = new Array("/store_templates/greatmags2007/images/headerImage.jpg","/store_templates/greatmags2007/images/headerImage2.jpg","/store_templates/greatmags2007/images/headerImage3.jpg")

function pickimage() 
{ 
//This line picks an image at random from the list you entered above 
var bgimage=backgroundSrcs[(Math.round(Math.random()*(backgroundSrcs.length-1)))]

//This line applies the background image to your masthead 
document.getElementById("header").style.background = "url('" + bgimage + "') top right no-repeat"; 
}