1. Make sure that you have garmin usb drivers installed, updater.exe is opened with usb option selected and your gps is completely switched off.
2. Now place your thumb finger at the top left of the gps and power on your gps by connecting the usb to pc. GPS will automatically goes to update mode and click ok at updater.exe on the pc. Dont remove your thumb finger until you see that message that update is successful on the pc
3. For exact position of the thumb finger you can see the picture that was posted in post#1.
4. Its not hard just do trial and error to get updater mode.