Method 1: Background templates
The simplest way to add a background is to right-click on any image and choose Make Spread Background Image. Note that this will change the layout to a new layout specifically designed for background images in mind.
Method 2: Add background without changing layout
If you would like to add a background without changing your existing spread layout, follow these steps:
- Double-click on the spread to enter Designer View.
- Stretch any image across the entire spread.
- Right-click on this image and choose Arrange > Send to Back to make it a background.