CD Key?

[twitch.tv/vbossi32]

Hi guys i buy Magicka collection on Amazon this week, when i play it says the game will ask for a cd key and i need put the key provided for that little popup... some1 know how to put the key? because the game never ask for it thanks

[[Lemons] w!z@rD]

The key is useless. It's just Steam. Every game must have a key, no matter what it does..