Have you read the manual/multiplayer tutorials? It's not easy.
You're already missing about 4 steps. If you haven't done your homework, it's only going to get worse.. I figured this out with just a quick peek at the manual:
Connect to a signalling server. Upon successful connection, On connected will trigger.
Triggered after successfully connecting to the signalling server. In order to join rooms, it is necessary to next log in to the server.
Once connected, log in to the signalling server. Players must log in before they can join rooms. Upon a successful login, On logged in triggers.
On logged in
Triggered after the Log in action if the login is successful. Once logged in it is possible to join rooms. (yes, it literally mentions that on every single one of those manual entries)
NOW you can request the room list...