I'm ready to chuck the Dakota out of the window, but I think it is mainly *my* fault...for being Dumb

I've created a number of online running and cycling routes. I can then download these as either tcx, gpx or gpx route files. What I would LIKE to do is to put them onto my Dakota 20 so that when I hit "where to?" and go into "routes," it will give me notifications on when I should make turns etc...

HOWEVER whilst I can get the GPX files to show up as tracks and see them on the map, I can't get them to show up in routes. I have tried saving as gpx routes, and or plain gpx files, and then putting into "new files" on the SD card, or into "GPX" folder on the device itself but they don't show up in "routes".

I KNOW this must be me being an idiot but I could really use some idiot proof help her to help me take a file and get it into the right place

thank you in advance!!!!