Navigation
There are two key navigational elements: the header menu and the section menu.
The header menu is universal across the site and set in the Appearance – Menus section as per this screenshot which shows the structure of the current site:

This creates the header menu at the top of the page. On a Mobile display, the menu will also show the sub-navigation.

The Section menu is shown on the right of a Parent page. It can be set independently of the header menu.
Sections also need to be created separately at the Page level. On a page, set the Page attributes to the required Parent page and set an order.
On a mobile display, the section menu is shown under the main content.
