1) Download the progam that will let you add VC to your Xbox Live Account.
2) Put your NBA 2k13 save onto your USB and plug it into your computer/laptop.
3) Open the “VC” program and insert your save game.
4) You will notice your current amount of VC in the program. Simply change that amount to how many you would like to have.
5) Click “Save” and then put your USB back onto your Xbox 360.