Instructions
Insert your "Call of Duty: Black Ops" game into either your Xbox 360 or your PlayStation 3.
Wait for the company logos for the game's developers to play on screen. Once they're over, the "Call of Duty" logo will appear. Press "Start" on your controller at the "Press Start" logo screen for the game.
Select the "Zombies" option from the main menu. This is the third option in the menu, beneath "Solo" and "Multiplayer." This will load the Nazi zombie mode. Select "Solo" (the fourth of the four options on screen) to begin playing a solo Nazi zombie deathmatch.