The first thing you will want to do with regards to chat, is set it up in the way that is most appropriate for your own site. The main settings can be found in the following location
From here you can set up the various preferences. If you set the "Show Chat Rules" setting in this area, it will give you an editor to enter the rules of your chatroom. These will be shown before a user enters.
In addition to the main chat settings, you will find other settings within each member group, which will let you set who can access, moderate, and send private messages.