Things You'll Need
Instructions
Insert the USB flash drive into one of the USB ports on the front of the Xbox 360. The ports are hidden under a door on the right side of the face.
Turn on the Xbox 360 and go to the dashboard. The console will boot to the dashboard automatically if you turn it on with no disc inserted. If you have a disc in the console, hold down the Xbox logo button to bring up the dashboard prompt.
Open the "My Xbox" menu and choose "System Settings."
Open "Memory" and select "USB Storage Device." The console will ask if you want to format the entire drive or just a section of the drive.
Select "Configure Now" to format the entire drive.
Select "Customize" to specify a partition. Move the slider to the amount of space you want to format and select "Configure."