multicasting using C++

I have multiple clients connected to a server. I have a 3D visualization with interactions on each client(Do not bother about this,my question involves only C++). Any changes made in 1 client has to be "multicasted" to clients that are subscribed to the group ID. I know what information needs to be sent to the multicast group. But I need to know how to set up a group ID, how clients can join the multicast group and how a client sends a message to the multicast group. Need C++ source code to implement all the above features and explanation. ## Deliverables 1) Complete complete source code of all work done. ## Platform Windows XP