hoe to create a server?

i am quite new in unity and i am trying to create an Multy-Player FPS similar to cs 1.6
My problem
how can i create a server and any player can connect to the server just by clicking join server

 

Download the network example from the unity support page. It will tell you how show you multiplayer and master server in action

And without quite some programming on your end, there won't be any multiplayer shooter game at all, just to point that out upfront

 

thanks