Chat Rooms
The chat software provided for you, is called the Melange Chat. When you click on this link, you will see the code that you can copy and paste into a regular HTML file. When a user visits this page, they will be asked to enter a nickname. Upon submition, the user will enter the chat with that nickname.
Using this method is not the best, in terms of chat. This server runs over the HTTP protocol. The HTTP protocol was designed to serve up webpages. This means that it will send a page to a user, and then stop. It is not a persistant connection. Melange will simulate this by refreshing the page very often. Because of this, it can result it crashes, because this just wasn't how the HTTP protocol was designed.
As far as the Java chat goes, it should provide a more stable enviroment, because java can use backend code to connect to the chat server better. However, we have not tested it, and do not know how well it will work.
If you are serious about providing a chat, I strongly recommend you look into IRC. IRC stands for Internet Relay Chat. It is designed to be a chatting enviroment. We do not allow IRC daemons to be run on the server, but there are several IRC chat servers available. Many will allow you to register a channel, where you can invite people to chat.
To read more about IRC, see this link.