Peer to Peer IDs

Hello All,  I would like to build a small chat application. My question, is  in regards to direct routing. How does, a Flash player, communicate with specific peers or more specifically get its peerIDs? In my example, i want users to chat in private room and send short messages back and forth. NOT to broadcast messages to all members of who belong to a group.

Is this a complex thing to do? Appreciate it if you could give me some information on this.