How to Update Garmin Nuvi Maps-converted

Like paper maps, a country or region is split into
several smaller maps. All Garmin maps have the
extension '.img'. Before these maps can be used
on the GPS unit, the maps have to be bundled in
a single container. Usually, Garmin own software
MapSource bundles the maps and stores it in the
Garmin folder of the unit's memory.
Garmin supports the following container files:
gmapbmap.img Typically this is the preloaded
base map.
gmapprom.img Typically this contains the
preloaded detailed maps.
gmapsupp.img Typically the maps uploaded by
Garmin MapSource.