Instructions
Place the memory unit into one of the memory unit slots on the back of the Xbox controller.
Plug the controller into one of the controller ports on the front of the Xbox console.
Turn on your Xbox with the game you wish to save and play through it until you reach a save point.
Select "Memory Unit A" or "Memory Unit B" (depending on which slot you placed the memory unit in) as the save device when prompted to save your game. The game file should save to the memory unit.