Icon in menu navigation tab

Hi thanks for the great plugin. I am using the cbox theme and trying to add an icon to my group menu. I have changes ‘Pages’ to ‘About Us’ and would like to include an icon in line with the rest of my menu. For example when using BP Group Hierarchy I used the following for Member Groups:

#nav-hierarchy-groups-li,
#nav-hierarchy:before {
content: “{“;

With BuddyPress Group Tiny Chat I used:

#nav-group-chat-groups-li a:before,
#user-group-chat:before {
content: “””;
}

However I can’t work out what css code I should use to get an icon in my menu for my ‘About Us’ page. Could you point me in the right direction please?

http://ww.wp.xz.cn/plugins/buddypress-groups-extras/