window.onload = choosePic;

var myPix = new Array("photos/hpPhoto01.jpg","photos/hpPhoto02.jpg","photos/hpPhoto03.jpg","photos/hpPhoto04.jpg","photos/hpPhoto05.jpg");

function choosePic() {
	randomNum = Math.floor((Math.random() * myPix.length));
	document.getElementById("myPicture").src = myPix[randomNum];
}