Admin Forum:Chat greeting?

Hello. Ive noticed on some chats they have made there one unique greeting when you enter the chatroom, and there own unique goodbye message when they leave. Ive serched all of over to find how to do it but i cant seem to find it. How can i do it on my wikki? Thanks .Skye
 * Just edit the following two pages of your wiki:


 * MediaWiki:chat-user-joined
 * MediaWiki:chat-user-parted. 09:54, September 7, 2012 (UTC)