Adding Pages To Navigation Menu

From the WordPress admin area, hover on the Appearance menu item in the left menu, then click on Custimize.

At The Customization page choose Menus:

After Clicking the specific menu you can edit the pages.

To add a new page or a new folder of pages, click the + Add Items button. To place a page in a specific folder, drag it into that folder.

To edit the Footer menu, return to the menu and select one of the selected menus:

Note: Learn more about Menus here