How to Download?

This is going to sound super ignorant given that I've patched this game in the past; but since they've gone to electronic download from CD, I'm way out of the loop. I just bought a copy of 2K13 from Greenman Gaming. Do I need to install Capsule to download the game? I had some trouble when I tried Capsule when downloading FIFA, so I used Origin to download FIFA 13, as directed by JaoSming, and just used the code that Greenman gave me, and was hoping to be able to do the same for NBA 2K13. So, after purchasing the game, what is the best way to download it so I can enter my code?? NO, I did NOT get the game illegally.

http://store.steampowered.com/about/?snr=1_4_4__11

Once installed: Games -> Activate a Product on Steam -> Enter key

http://store.steampowered.com/about/?snr=1_4_4__11

Once installed: Games -> Activate a Product on Steam -> Enter key

In the process of downloading now, thank you sir.