From the WordPress admin dashboard, go to Appearance>Menu
Create a new menu and select the pages or custom links to add to the menu
Save.
Similarly, you can, if you want to, create more menus and later add them to the footer area.
Once the menu is created, go to Appearance>Widgets
From the Available Widgets on the left side, select Navigation Menu and drag it to the footer area where you want to place it.
Expand the Navigation Menu, enter Title for it (the title will appear as the header of the navigation menu on the footer), and from the Select Menu drop-down, choose the menu you created for the footer area.
Click Save.