Asynchronous Communication

hop of those help? I think you are little mistaken by word "server". It is not web server, it is ordinal computer (or even application) which serves request. So for you multiuser chat you need to create 2 kind of application - server and client. Server will listen to clients and reply them. Usually, there is only one server and lot of clients. I suggest you to start writing simple server/client program and then improve them. Create server which will serve only 1 user at time. It will listen to specific port on local IP. I use Task to simplify program.

        byte[] ba = new byte[1024];
        new Task(() => {
            Output("Going to listen to messages...");
            Socket listeningS = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            // Listening to local address. You should listen to external IP for real server
            IPEndPoint ep = new IPEndPoint(IPAddress.Any, port);
            listeningS.Bind((EndPoint)ep);
            // One and only client at a time :)
            listeningS.Listen(1);
            while (isRunning)
            {
                // Accept client, receive data and send it back
                Socket clientS = listeningS.Accept();
                int total = clientS.Receive(ba, 0, ba.Length, SocketFlags.None);
                total = clientS.Send(ba, 0, total, SocketFlags.None);
                // Client will open new connection (but later it is possible to use same)
                clientS.Shutdown(SocketShutdown.Both);
                clientS.Close();

            }
        }).Start();

    byte[] ba = Encoding.UTF8.GetBytes(message);
    Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
    s.Connect(IPAddress.Loopback, port);
    total = s.Send(ba, SocketFlags.None);
    total = s.Receive(ba, 0, ba.Length, SocketFlags.None);
    if (total > 0)
    {
        Output(Encoding.UTF8.GetString(ba, 0, total));
    }