This is a very simple Chat Room applet.
Load the Applet from the server.
Note that if you try to load it from your local machine as opposed to a server, you won't have much luck, since Java Applets are only allowed - for very good security reasons - to open a network connection back to where they came from! So, the applet will start, but you will NOT be able to login. Load it from the server instead.
Or, you can Use The Source, Luke. See also the server source. Also see shared Chat class source. Source files with line numbers: Chat.java, ChatRoom.java, ChatServer.java