Not sure that you can. Publisher is designed for static pages, and a guest
book is dynamic. If I were trying to do this then I would first go to my
webhost and see if they have a guest book module or program, and if so, its
possible that you could either link to that, or possible get a code snippet
to insert into your Pub doc using the insert html code fragment feature. If
still no joy, then perhaps Google for guest book code, and see if you can
find something that way.
DavidF