Go to the giveaway page, click buy now https://www.licente-jocuri.ro/uefa-euro-2012-origin-key.html
Register and login to the site ( i used facebook registration)
Go back to the cart, checkout (no need to pay, because its free)
Wait for the email, and click on the link from the email
you will see a cd key on the image, activate on origin and have fun.