After you have created a portal and added books and pages to the portal desktop, you should determine the type of navigation to use between books and pages and set the default page that appear when users access the Desktop.
The main body of a desktop is contained within a main page book that is created automatically when you create a portal. You set navigation properties on this main page book.
To set up navigation on books
Note: If you created your own navigation menus by copying and modifying the default menus, they are also available for selection.
You can use the Portal Samples for to change and view navigation modifications. The Tutorial Portal also contains different Look & Feel implementations.
How Do I: Use Drop-Down Navigation in Portals?
Tutorial: Changing a Portal's Look & Feel and Navigation
The Portal User Interface Framework