Newbie with a Garmin Nuvi


I am new to OSM and this Garmin Nuvi. A friend gave me his Garmin Nuvi 265w but the maps are out of date and I am partially computer savy. I would like to update the maps on this older Nuvi but keep messing it up. Any help would be appreciated. Thanks

These are the providers of Garmin suitable openstreetmaps.

There are instructions on the above site and the Lambertus and Bbbike sites and most likely the others sites too.
First rename other gmapsupp.img that may already be on your micro-sd card then all you need to do is download a copy a gmapsupp.img of the area you want and copy it to the “Garmin” folder on the micro-sd card on your Nuvi 265w. You most likely need to unzip the download to access the gmapsupp.img
I would leave the files on the internal memory of the Nuvi alone.