Have you read KiwiJochen instructions carefully?

You should NOT try to access the navigation system. You should NOT turn your radio on.

I assume you are able to extract any CD currently inside the nav unit and that you are able to insert a different one.

The system should automatically become aware that a system CD has been loaded into the navigation unit and should automatically start the upgrading process.

Upgrading OS is quite a simple and safe enough process, if carried out correctly, and an extremely risky process if the correct procedure is not strictly followed.

So read the instructions once and again, until you are satisfied you fully understand every step, and then follow them strictly.

Good luck.