Here is how to do somethings you Can do in the chatbox as a regular user:
/clear Delete the messages from the Chatbox
/cls Same as the '/clear' command
/me In the beginning of a sentence, this command will be replaced by your username (ex: /me eats a delicious pizza" will display "Nickname eats a delicious pizza")
/exit Disconnect from the Chatbox. You can also precise the reason that will be visible for all members connected (ex: /exit reason)
/abs Send a message noticing that you're absent. You can add a reason that will be displayed in the message and visible by all members connected to the Chatbox (ex: /abs reason)
Hope That Helps You Out
P.S. If You Need Help With The Chat Box Just Post It Here