Apple Aperture - Manual (Page 359)

Chapter 19 Creating Books 359
III
The Pages panel on the left shows thumbnails of your book pages. You can scroll
through the thumbnails and click one to select a page of your book to work on. A
larger view of the selected page appears on the right.
Books are based on a theme, or design, and master page layouts that present your
images in a standardized way. Click the Theme button to see the themes you can choose.
Selected book album
Select the page you want
to work on here.
Selected page
A larger view of the
selected page appears
here.
Select the theme
you want here.