//Edit this line to list all of your background images
var backgroundSrcs = new Array("images/sign.jpg", "images/mailbox.jpg", "images/water.jpg", "images/water2.jpg", "images/cabin.jpg", "images/flags.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 = "#000 url('" + bgimage + "') no-repeat right"
}