Chatroom integration

I have a integrated chat room that I get for free from my hosting provider. To enter it, you put in your "nickname" in a box and hit enter. I understand that when logged in the site dynamically puts your "login" name on the upper most block to the right. Is there a tag for this that I can just put into the code for the block? My purpose is that the user will just hit "enter" and go into the chatroom using the name they are logged into the site with and submit content with... I believe this will reduce confusion and possible impersonation, and security is little issue since my users are, to be honest, not very computer literate. Does anyone have any other approaches for this problem?
-Andy