In the Design menu of each page, the Backdrop feature lets you set a custom page background — whether it’s a still image; a video; a Google Map; a color gradient, or one of the many visual effects available. After you set a Backdrop, there is an option to “Split” the page, which displays the Backdrop and the page contents side by side.

In this Video:
Working with Backdrops
Using the Wallpaper Backdrop
Setting up a Video Backdrop