It's easy! Commands start with /cmd prefix. Then you type the command with eventual arguments.
Let's take a look at few examples.
Server will help you If you send unknown command.
Some commands are available only for admins (dns or akick).
You can use:
No arguments. Simply lists online servers with players.
The argument is a part of the server name you look for, i.e. "wild fort".
The argument is a part of the player nickname you look for, i.e. "niro" or "woned". Shows when the players has been last seen.
The argument is a valid Perl Compatible Regular Expression. It's the most interesting command. It shows all online players matching specified regular expression and the servers they're play on, i.e. "/~/" will show all players with tilde in it's nickname.
No arguments. This and the next commands are the examples of using grep so you can find clan players based on tags (CT, dBd, DS, ID, Sp, X and so on).
Don't forget you have to authenticate to use Custom Commands.