var ar = new Array("<IMG SRC=html/HomePic1.jpg width=385 height=286>", 
"<IMG SRC=html/HomePic2.jpg width=385 height=286>",
"<IMG SRC=html/HomePic3.jpg width=385 height=286>",
"<IMG SRC=html/HomePic4.jpg width=385 height=286>",
"<IMG SRC=html/HomePic5.jpg width=385 height=286>"); 

var num = Math.floor(Math.random() * ar.length);
document.write(ar[num]);