I want to use following code for Clickable background.
<style type='text/css'>
BODY { background-image:url('my.aspx?id=001') }
</style>
where "my.aspx?id=001" will return an image randomly, but i also want this background
to be clickable (Navigate to my randomly specified Url)
How is it possible ? Share the Ideas and give me chance of thanks.

background images cannot be "clickable", you would have to overlay an anchor element.

and the random background would be better done server side NOT with javascript.