I got it! I cut and pasted the directions from the PDF (in French) into Google Translate and was able to figure it out. There are two maps in the set. The one block with the text "Sentiers Motoneige Quebec" just has the trails in it with a transparent background. If you already have a background map that you want to use, just pick that block; otherwise if you pick BOTH blocks of maps to transfer you will get their generic background map that will overlay what you already have effectively blocking out or covering your existing / preferred base map. At least this is what I've found on my Garmin Montana 650t.