Step 10 - Running
Now you should have two folders.
Open "ServerBuild" and run the game.
The game shall start and the player spawned ( this player is the player obejct where game is running ).
Open "Client Build" and run the game.
Your player shall be spawned and the previous player ( on the server ) will appear on your instance.
All players shall appear in both instances and all movement will be reflected in both instances ( you can move by using W-A-S-D keys ).
Now you also can run many instances as you wish.