Chat Server: how to?

Hi,
I want to create a Chat Server, like yahoo, ms messenger or mirc.
Can I use the chat client with two different and private IP (es: 192.168.10.1 and 10.10.10.1) in different LAN?
How can I know the way to send, the chat message in the different lan, to the correct client?
How can use, for this scope, the Winsock control?

Help Me Pls