Here are some simple instructions for redeeming your uPlay keys:
What is Uplay ?
The Uplay Client is a launcher which allows you access to all of your Uplay-enabled titles as well as extra content via the rewards system as described above.
Uplay is accessible from: https://account.ubisoft.com/ or from any Uplay enabled game.
Redeeming your Uplay keys
1. Open up your My Games page and locate your uPlay key. Click the "Redeem" button to generate your key. Copy this to your clipboard. If you have not yet downloaded the uPlay client, make sure you have done so.
2. Open up the uPlay Client and log into your account. From there, click the "Games" button at the top. You will have three options available. Click the "ACTIVATE PRODUCT" button and enter your Key.
3. Verify you are activating the correct title and redeem your game by clicking the "ACTIVATE PRODUCT" button. Once this is done it will automatically add the game to your library.
4. That's it! Once you've located your game you may go forth and play! If you're unsure if your key activated, go to your Account Details to check. For all other issues, please contact Ubisoft Support here.