Strophe.js MUC: creating a room and joining more than one room

I'm creating a chat website and I'm using Strophe.js and the Strophe.muc.js plugin. The single chat functionalities work fine, but I also wan't to implement a group chat function where users can create rooms and invite other users to their room. Using the muc plugin, I can create a room, but the problem is that until I don't configure it (I guess), other users can't join and the room isn't persistent. I know that the muc plugin has configuration methods, but I don't know how to create the config Form object, I have no idea how should it look. This would be my first problem. Second: Is it possible that I join more then one room and get messages from all the rooms I'm in? If not, then there's no need to give me an answer to my first question...