A useful feature of the Verge viewer is "Publication Signposting"; when adding headers to your pages in the Publication Settings, they will be shown on the thumbnail pane at the bottom:
NOTE: If two pages displayed at once have different headers, the second of the two will be shown.
To apply page headers:
1) Sign into the Zmags Publicator, click "All Publications" on the left.
2) Click the name of the publication you would like to add headers to.
3) Click on the 'pages' tab at the top.
4) In the list, find the page you would like to add a header to. Click the pencil icon.
5) Type the desired header into the provided box and click 'Save'.
6) When finished adding headers, click 'Save' at the bottom.