Go to here:
http://www.info-rc.net/?page_id=218
And under 'GM Software' download the AS-Soft (which is the main GM program) and also the Drivers, which are needed to get the USB working.
Once you've got the GM software up and running, you need to:
1. Connect everything up
2. Select the correct port.
3. Select 'Fix port'
4. Click 'Receive data'
5. Press the little button on the GM USB lead circuit board.