Okay,

Thanks for your reply's.
I succeeded to updated the Garmin with WebUpdater but then I'n a little lost.

On the Garmin I have found:
.System
gmapprom.img
gmapbmap.img
GMAPTZ.IMG

I assume (I am sure )I have to replace them (GMAPTZ.IMG ??) but the problem is how to do.
I found a lot of Garmin maps

Garmin City Navigator Europe NT 201610 Map Source Data with msi installer Unlocked
or
Garmin City Navigator Europe NTU 201630 )for Garmins who can work with unicode)

How to go on because that isn't clear for me?