Changing Username: You can change your username by clicking on your name to the left of your text-input box, or you can type /nick new-username (this input will be invisible to everyone else in the chat).

Private Chat: You can chat with another person privately by clicking on their name to the right, and selecting "private message"--it will open a new chat window for just the both of you.

You can also join new rooms by typing /join *room-name*--if a room by that name doesn't already exist, it will be created. You can be in multiple rooms at once, and switch between them using the tabs.

Actions: Type /me *action* and it will appear as something like:
       *My-Username jumps off a cliff

Leaving a room: You can leave a room by clicking the X-icon on the room's tab, or by typing /leave

Moderators: Mods can log in by changing to their admin-username and then typing /identify *your-password*. Your icon to the right will change to a gold badge, denoting your moderator-status.
       -You can kick people from the chat by typing /kick *username*
       -You can ban people temporarily by typing /ban *username* *hours to ban* 
             *reason*
       -So, for example, /ban Naruto 5 I don't like you, means that the user Naruto's
             IP is banned for 5 hours, and the reason is "I don't like you". If the
             person's user-name has a space in it, like Naruto Uzumaki, you'll need to
             use quotes, like "Naruto Uzumaki". The default time for a ban is 1 hour.
       -You can unban people before their ban expires by clicking on the "Banned
             IPs" list and removing it from the list.