You can't add a guestbook or any of the add-ons with Yahoo! SiteWizards. To install add-ons, you'll need to open the page in PageBuilder or SiteBuilder. SiteBuilder offers the most sophisticated editing features, allows you to create nearly unlimited pages, and gives you the most control over your site.
Please note: Once you have edited and saved a SiteWizards file with another editor, you will no longer be able to safely use SiteWizards to open and edit your page. Learn more.