To add font icons in the menu (top and main menu):
- Go to Plugins -> Add new, and install the Font Awesome 4 Menus plugin.
- To preview all available Font Awesome icons, go here. Click on an icon that you want to use and then copy its code.
- Go to Appearance -> Menus, select a menu that you want to edit and paste the icon’s code in a menu item. Save the menu.
- If you want to add only one icon to the menu(without text), add this td-only-icon to the icon’s code for a better alignment.