Also, achievements will be disabled as soon as you start entering these codes, so unfortunately you won't be able to cheat your way to completing any challenges. This may sound obvious, but it's worth reinforcing that using some of these codes (especially in combination with others) can cause glitches, mess up ongoing storylines, or crash your game entirely, so make sure you create a back up save and keep it separate before you start playing around - otherwise you may find you've permanently broken your progress, and nobody wants to deal with that in a game the size of Skyrim.
Unless otherwise stated, entering the same code a second time should turn it off again. You can enter multiple codes to stack up various different effects, then hit tilde once again to return to the game and reap the ill-gotten rewards you've given yourself.
As with many other PC games, entering Skyrim console commands is simply a case of pressing the tilde (~) key to open up the developer console, then typing in the command code in the correct format.
