The left part of the window will display the users connected to the server, how they are displayed can be customized in the miscellaneous preference. The chat window allows you to chat with users on the server through the public chat. You can use the normal CTRL+C, CTRL+V, CTRL+A to copy/paste/select all from the chat window. The bot will now accept command through the public chat window prefixed with !, e.g. !command instead of command. This makes it possible to test command offline without connecting to the server or even having the server running.