This is the "Layout" tab from "Project | Documentation Options".

Margins

You can enter values for Left, Right, Top and Bottom. Values are in millimeters.

Distance from Page Border

The values for the Header and Footer are on top of the values for the Margins. A header or footer height of 10 mm is an average distance.

Include These Pages

All the pages that you can add are listed here, with options to add blank pages in between. This is useful if you are trying to ensure that the Table of Contents opens on the right for example. Then you might want to add a blank page after the Front Cover.

Space after Heading/Topic Titles

Type in the number of blank lines you want to use after a Heading and after a Topic Title. The Help Text will appear after this, so you may want to create a nice empty space to make the Heading or Topic Title more distinct.

Layout after Help Text

The Text/Symbols after Help Text allows you to indicate to the reader that the Topic is complete. This may be by using the symbols "-o-", which you find in some books at the end of a chapter. Or you could add a horizontal line. You can also specify how many blank lines should be added after the Help Text.