Instructions
Insert the game disc for "Call of Duty: World at War" into your console (for example, Xbox 360 or PS3) and wait for the game to load. If it doesn't load automatically, click on the game in the console's main menu.
Select "Nazi Zombies" from the "Call of Duty: World at War" main menu and then select your map. The default map is "Nacht der Untoten," and it will be selected automatically if you don't select a map.
Click "Start Game" and wait for the map to load on-screen. Press the "A" button on your Xbox 360 controller or press the "X" button on your PS3 controller to jump high. If you ever find yourself surrounded by crawler zombies later in the game, click the left stick to run and then press the "Jump" button to perform a high jump to get over them.