Download from here [Only registered and activated users can see links. ]
navnet_Garmin_v252-NT.exe
Run the .exe and install the map in Basecamp, map isn't locked. Run Mapinstall and transfer in gps.

Forget single pc install .imgs, these are parts of pc installation. You cant install that way, or at least, it needs some skills and Mapsetoolkit program.
Why don't you want to read FAQ and make things simple?