This Collector's Edition contains the 3 DLCs "Relic Rune Pack", "Character Skin: Dark Dracula" and "Character Skin: Armoured Dracula" and here's where you can find them in-game:
Relic Rune Pack:
Once you’ve redeemed the code, start playing the game as normal. This ability will become available once you have picked up your first relic!
Dark Dracula:
Select 'Game Options' from the 'Configuration' menu in-game after you’ve redeemed the code to access this DLC.
Armoured Dracula:
After redeeming the code, you will be able to select this DLC by choosing 'Additional Content' from the Main Menu in-game.