How do you create a private game server

Please do not create a WoW private game server because WoW private server's violate the terms of use.

Wrong. It is known that if someone creates a private server of "WoW" or of any other game, they add there own add-ons to the game making it bellong to them and not a copy of blizzard work. If any one creates a private server they will make sure they have not 100% coppied a game, making it legal to use. The company can try to shut you down though if you find out your private server.
I have just read the terms of use and what i said is true, it can be legal if you make the right steps.