This was already covered in the chat room primer that was written up by one of our members. But for those who havent seen or read it
if you want to create a private chat room you would type /join #name of room with no spaces. So if I wanted to create a room called
devilsden I would type /join #devilsden and if I wanted to make the room private I would type /mode #devilsden +s
For more info about the chat room you can look here
https://www.freecatfights.com/forums/index.php?topic=64047.0