A question came up about adding social media icons to the navigation bar in a twenty eleven child theme, answers were given changing code in the header.php file.
The question came from a novice who was not sure about changing code, so thinking about this and how we can use WordPress to do most of what we wanted we came up with a simple solution.
This tutorial may help others and shows one way of using the Menu CSS Classes option, in the custom menu area.
David