So I just ordered this. Basically you create an account on the greenman site, pay, then you get the serial immediately on screen and in an email receipt (note - I used visa - not sure if paypal is different). When you get your code, fire up steam. In the bottom left hand corner, click on add a game.... then activate a product on steam... then just paste in your code. Boom. It's registered and you can start downloading. It comes in at around 7 gig.
