Your portrait pages can be decorated in the same manner as any other page in your yearbook.
Add Shapes to create banners and other decorative effects.
Add decorations from the Elements tab.
And add a background from the Background tab.
Add photos from the Photo tab.
Use the Order tool for any element you add to your page to push it behind the panel. In this example, a decoration has been added to the page, then moved to the back so it appears behind the title and panel.