Step 1: Download and install Origin application on your PC. The link to official download page can be found here.
Step 2: Launch the Origin client. Login to your account if you already have one or register a new account.
Step 3: Select "Origin" from the menu in the top-right left corner. In the dropdown menu select an option "Redeem product code".
Step 4: Enter the cd key that you would like to activate on Origin and press "next"
That's it! Your game is now activated and you can find it in your Origin library. Head over there to download and play your game!
By confirming the delivery, you agree that the order has been received.