Scrolling page with locked div

Hi All - I have a screen that I scrolling thanks to a previous question that was answered for me.  I forgot that I need a banner at the bottom that doesn't scroll.  It has to be at the bottom of screen regardless of what size the window.  The browser window isn't full screen so I would need the 100px high banner to stay frozen over top of the scrolling if that makes sense.

I'm using this code

var savpos = -1;
function pageScroll() {
    scrollBy(0,1);
		if (savpos == document.body.scrollTop) { // didn't scroll - end reached

			// TODO: redirect
			// window.location.href = '...';

			// to test, show alert
			 window.setTimeout(pageNext,6000)

		} else {
			savpos = document.body.scrollTop;
			scrolldelay = setTimeout(pageScroll,10);
		}
}

function pageNext() {
//	 alert('done');
	 window.location.href = './eventboard.php';

}