Kale has one main menu location “Main Menu”. This is the top header menu right under the logo.
On smaller screens (such as mobile phones and some tablets in portrait mode) the navigation will collapse into a button that can be clicked to drop down the navigation items.
To set this up, go to Appearance > Menus, add a new menu, and assign it to the “Main Menu” location. You can add posts, pages, custom links, categories, etc. to this menu. For more information on how to create menus, please read https://codex.wordpress.org/WordPress_Menu_User_Guide.