How do I proof pages?

To print pages for proofing, click the File menu and select Print.

With a spread open, select the File (three stacked lines)> Print. You will be presented with a dialog box where you can select to print spread or single pages as a High resolution or Low-resolution PDF. The description of High and Low-resolution PDF is provided so that you can select the appropriate one.
You can choose to either print or download the PDF of the spread.