Make sure you have installed the SPi Suite first.

To check for updates you need to run the SPi Suite, you can run the SPi Suite from your start menu (Start > All Programs > SP Diagnostics > SPi Suite) or from the SPi Notification Icon* found in the left hand tray at the bottom of the screen (Right Click and select SPi Suite)

Next click Get SPi Updates and follow the instructions.

*The notification icon is a tool we use for informing you of new application releases, if you click "Check for SPi Notifications" this only checks if we have sent you a new notification, it does not check if your SPi is up to date.