How do you make online Servers for a game?

Hey, I’m currently creating an online game (to download). And I don’t know how you can create Servers for people to play online with. Help please?

Check out this series from 3D Buzz.
http://www.3dbuzz.com/vbforum/sv_videonav.php?fid=6c3946098163324906cd01e73379764b

You have to be a member, but membership is worth it.

Probably best to go with a service that already provides server side support that integrates with unity, photon is one example.