The main navigation located in the header displays the first three levels of links assigned to your navigation tree.

Content > Link Lists > "Navigation Links"

The custom icons are created by entering a custom class in the icon class field.  To see a full list of available icons http://dentonbible.monkpreview3.com/_assets/fonts/icons/ or https://dentonbible.org/_assets/fonts/icons/ when your site goes live.