This is the theme setting for your Menus.
Go to Appearance and click Customize. On customize click on ‘Menus’
Or you can go to ‘Appearance’ and click ‘Menus’
Fill in the Name of the Menu then hit the button Create Menu
To Add a Page on a Menu, Just click the Page Title and hit add to Menu button.
To display the menu on Homepage, just choose ‘The Main Menu’ display location option and Click Save Menu