Got rFactor 2 as a gift, don't understand how to register

Some nice friends bought the game to me and sent me a copy of the purchase e-mail including what looks like the serial number, something called Purchased Coupon Codes. It also includes the receit of the purchase itself. How do I go about regestring and activating the game?

Thanks in advance for any help or pointers.

 

Here are the instructions. Feel free to ask if you have any more questions.


http://rfactor.net/web/rf2/rfactor2-purchase/

 

Thanks you! I have been on the above page earlier but tried again. This time it worked

 

Thanks mate, I solved it now