How to add information for legend

I don't know how to add information for legend , I want to show color of group users when they log in
For example : color of Admin is red ...
Thank you very much

"ACP / Users and Groups / Group Control Panel". there you can modify existing or create new groups. You can also give the group a color that users in this group will have as well.

Note that you eventually have to set "Users and Groups / User Settings / Colorized Usernames enabled?" to 'YES' as well.

you can add detail in description.

Oh , I did thus, Sunny_D but I don't see color of groups that I created except color of Admin and moderator ( they still exist )
For example , I created group that Its name is XXX and its color is yellow . After that , I allow one user belong to the group but when the user log in , Its color isn't still yellow
So what must I do ? Thanks

You can read This tutorial