Finding the right bricks for a client/server app

Hi,
I was hoping to get some directions to get an idea of which classes and approaches I need to use to create a client/server application with client registration and authentication. I want to create a pokerroom. All the poker related stuff will not be a problem... but I don't have any experience with client/server applications. Things I would like to know include:
- Which way is used to set up connections for this kind of app
- How to keep track of the different connections/clients
- Authentication
- ...
I don't expect code samples... rather general guidelines to the right classes, frameworks, ... to use. Then I can start with some pointed research.
I know this sounds like a very long shot, but I have the advantage that I have already a very good knowledge of networking (10 years of experience as a system and (certified) network engineer), so that probably helps to understand the network related processes involved.
Tnx!

Network communication is performed mainly with classes from the System.Net and System.Net.Sockets namespaces. Start by checking out the TcpListener, TcpClient, NetworkStream and Socket classes. For a simple example of a client/server app, follow the CodeBank link in my signature and check out my Asynchronous TCP thread.