I can’t locate the menu
All menus used by your theme are automatically listed in the “selector” combobox. If the menu you’re looking for isn’t listed, you can either specify it manually or use the “locate on website” button.
The “locate on website” popup makes an educated guess about what HTML element might be the menu, using common HTML patterns used by WordPress. If that also does not find the right menu, you can still specify it manually by typing the selector (for example ”#my-menu”) in the “selector” combobox.