How send messages and get

Now I can connect 2 users in a room, but I don't know how get and send message,

where send and get messages normals in a room  ?

http://www.igniterealtime.org/builds/smack/docs/latest/documentation/extensions/ muc.html

I'm a new, used muc.

Not exist a

AddListener - > send / get - > ¿¿??