Instructions
Turn on your Xbox 360.
Select the "Xbox Live" dashboard menu option. If your console is not currently logged in, enter your Xbox Live user account information into the box on the screen.
Wait a few seconds. Once connected to Xbox Live, the Xbox 360 will automatically check for any updates that are available for your system.
Select "Yes" when asked if you want to update. Your Xbox 360 will download the necessary files and flash the firmware on your console's hard drive. Be patient and do not turn off your console while this is going on. Once the firmware update is complete you will be notified on-screen.