From the Pages sidebar, you can reorder the pages in the navigation by dragging and dropping the pages. To create a sub-menu, drag and drop the page title directly on top of the parent page.

To rename a navigation link, double-click on the name or select the Properties option from the menu. You can also choose to hide a page from the navigation by selecting the Hide from navigation option from the menu.

To change how the navigation looks on the page, choose General Settings by selecting the Gear icon from the top right. From here you can choose to display your menu on either the Top or Side.

You will be able to see changes to the navigation as you edit.