Sorry if this is dumb question.... I'm new to this...

I just picked up my new 07 X3 with Nav.
I'm about to order the USB interface and download the software to "edit" the Nav system.

But, I see reference to an OS DVD in the forums. Having not done this before I assume that the procedure is to make a copy of the OS or some specific files from the OS then edit those files. Then burn a new DVD and upload the edited OC back to the Nav computer.

Or, do I copy some specific files from the car, edit those files and then upload them back to the Nav computer.

But I could be way, way off here, so that's my first question. How does all this work? In short of course...

Thanks to anyone who can help me out....

Next. When I picked up my car Tuesday all I got was one DVD for the Nav. That was the mapping software. I did not get an "OS" DVD.
Was I supposed to? If not where do I get it, if I in fact I need it.