Top level pages on your website will appear in your website's primary navigation menu when they are published, and they have the "Include in top nav" option checked (found under the Settings tab for each page).
Subpages of top-level pages will show up in both the drop-down menus, and the secondary navigation menu that appears on inner pages just below the primary navigation menu, when they are published and have the "Include in top nav" option checked.
You can also include a tertiary navigation menu that will display links to sub-subpages in a column on the left-hand side of your inner pages. To activate this tertiary menu, simply tag the subpage page you want the menu to appear on with the tag layout2. When the menu is activated, and sub-sub pages that are published and have the "Include in top nav" option checked will show up in the menu.
If a page has the "Show sidebar" option checked, another sidebar will show up on the right-hand side of the page. Any page that has the "Include in supporter nav" option checked will show up in this menu.