How to use these codenames

First of all you will need to be able to open your command console and in order to do that you need to have a mod loaded. Then if you press the key below 'ESC' and left of '1' the command console will come up. Here you can enable cheats, change unreachable graphics options and more. Their are 2 different types of map load commands '/map' if you want to just load a map from any poin in the game for example "map 'mapnamehere' " and '/devmap' if you want to use cheats such as 'god and 'noclip' on zombies start first by typing '/developer 2' in the console and then follow it up by typing '/devmap 'mapnamehere' ".