Where to Redeem Modern Warfare 2 Code on Xbox 360: On the Console, Not InfinityWard.com

You redeem codes on the Xbox 360 console itself, not on InfinityWard.com. Infinity Ward is the developer; they don't handle code redemption.

Steps to Redeem on Xbox 360

1. Sign in to Xbox Live on your console.
2. Go to Xbox Live Marketplace (or Games Marketplace).
3. Select Redeem Code (usually under "Games" or "Account" sections).
4. Enter the 25-character code.
5. Confirm download — game/DLC will begin downloading.

If the code fails, contact Xbox Support directly.