Enabling a menu in your theme

The good news I have for you right now is that menus are already enabled in the structure of the theme we're creating here. Because we used the wp_nav_menu() function in the header of the site (in the header.php file), if the user creates a menu in Appearance | Menus, and then assigns it to the area indicated as Primary Menu, it will show up on the site, as demonstrated in the following screenshot:

If you want to have more than one navigation menu in your theme, you can register multiple navigation menu locations, let the user create multiple menus, and choose which menu goes in which location. To learn more about this, check out the Codex at https://codex.wordpress.org/Navigation_Menus.

Learning more
The wp_nav_menu() function is quite powerful, and can take a number of parameters that will let you control the classes and IDs, the name of the...