Sockets (urgent)

Hi all,
I'm quite new in C# and have no expirience in sockets.
I have to write any server component very urgent...
The component has to synchronize between 3 clients for perpetual work of one of them.

My app works with several clients, says C1, C2, C3.
I know IP and Port of each client. Every time should be only one working client. On the start my program has to send to C1 any parameters. If it succeeded the program sleeps all the time C1 works. If C1 failed down (the program or whole computer) my app has to catch it and try to connect to C2.
If working any client except C1 my app has to try if possible to connect to C1 and if yes, disconnect from C2 or C3 and connect to C1.

Any samples of code will be very helpful.

Thanks a lot,

Take a look at this.