Xbox Live subscribers can redeem codes by entering the 25-character code found on the back of an Xbox Live Gold card into the correct field on a computer, Xbox 360 or Xbox One. If you have a QR code, you can scan it with a Kinect sensor.
On a computer, go to the Xbox Live website. Click Redeem Code under the Xbox Live Gold tab and sign into the applicable Microsoft account. Click Redeem and enter the 25-character code on the card. Click confirm.
When redeeming on an Xbox One console, start on the Home screen and scroll right to Store. Select Games under Categories. From there, select Use a Code or say “Xbox, use code” when using the Kinect. Enter the 25-character code and click Enter. Subscribers can also scan a QR code if available using the Kinect sensor.
The Xbox 360 requires subscribers to go to Games & Apps. Select Redeem Code and then enter the 25-character code. Once finished, select Done and then select Yes to confirm.