BREW Theme includes support for Font Awesome, a very popular icon font.
You can add icons to any of your menus by specifying a Font Awesome code in the Description field for each link in your menu. For example, “fa-home” will display a home icon. See the Font Awesome website for a complete list of available icons.
TIP: If you do not see a Description field when editing your menus, click the Screen Options tab at the top of the menu editor screen and check the box for “Description”. This will unhide the Description field.