That is fascinating, I have an R3 and there is nothing back there. Lets skip that as I carefully went through the instructions and they stink.
Ok, first thing to do is download and install FLIP (I am assuming you are running Windows or Linux).
After FLIP is installed, plug in your Uno to the USB.
Short the pins 5 & 6 on the Atmega8u2:
This should initiate a "New Device Detected" event, manually select the driver folder from the Programs Files\ATMEL\FLIP 3.4.7\USB
(Should install the Atmega8u2 driver and it will require a reboot)
After rebooting, open the FLIP 3.4.7 program and click the Chip Icon and select the Atmega8u2 and click OK.
Now, click the USB Cable and click "Open".
If you get this far, get a screenshot and post it here.