Gilles Dufour wrote:
back to basics here.
1 machine is the client and the other one the server.
Basic: the client telnet to the server. You just need a server that allows telnet.
Or slightly more complex, the client open a connection the web server to download a page.
You then need a browser on the client and a web application on the server.

Your question is very generic.
If you are in the learning process, I would suggest to buy a book on tcp/ip and start from there.

Gilles.

I got more deep understanding about this part, Thanks for your sharing!