Can't figure out backup

Hi. The instructions for backup state about the disk image:
"This file is what you need to backup (or restore) if you want to backup or recover your data.
To select this file in the Finder, click on the popup and then click on the disk image in the list:"
1. How do you create the backup?
2. How do I click on the popup? What popup?
Thank you.
"This file is what you need to backup (or restore) if you want to backup or recover your data.
To select this file in the Finder, click on the popup and then click on the disk image in the list:"
1. How do you create the backup?
2. How do I click on the popup? What popup?
Thank you.