The listing, Xbox Live 48 hour trial has ended.
A 25 DIGIT ONE USE ONLY XBOX REDEEM CODE
Xbox 360 console steps: Redeem a prepaid code
Sign in to Xbox Live using the account for which you want to use the prepaid code.
Press the Guide button on the controller.
Go to Games & Apps and select Redeem Code.
Enter the 25-character prepaid code and select Done.
When prompted, click Yes to confirm the redemption.