Well pretty much a few times everyday someone will open inferno cows in a private game.
The person who makes it usually asks one of the staff to announce the game name and password.
The announcement will be sent to every player online just like it was a message from a friend but in blue lettering.
Also players sometimes make open games with the name/password of the private inferno cows in the description.
Possibly you've just gotten unlucky and haven't been online during the time's when they were running.
But I'm sure eventually you'll see one being announced soon and get the chance to participate.
Inferno Cows is definitely the best place to get experience and also a good place to find some items.