After the recent dashbaord update, this button moved.
From the Home screen, hit RB (right bumper) to go to Store (the tab name will change to Games) and click Browse All Games - in the upper right will be a button that says Use A Code. Hit that and enter your code.
Alternatively, if you have Kinect say "Xbox, use a code".
I hope this helps. Let us know how you get on.
Xbox Forums moderator. Xbox MVP. r/xboxinsiders moderator. Twitter: @13mxn
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