Scrolling Banner Ad - User to update

Hi All

My client has requested that I add a scrolling banner ad at the top of their page. Much the same as www.seton.co.uk. Does anyone know how to do this and then make it editable within Modx. The customer would like to change the images.

The customers website is www.kettlebelltrainer.co.uk and the back end is Modx 1.0.2.

Thanks

Phil