Billy, I just realized that you are trying to send the route to your Garmin 660. Unfortunately the 660 is NOT compatible with BaseCamp. Here is an excerpt from Garmin's own website:
The following devices are NOT compatible with routing in BaseCamp:
zumo 400 series
zumo 500 and 550
zumo 660 and 665
These devices may appear to take a route without issue however, when navigating the route, an error
message may appear. An alternate program to use is Mapsource. First download the map to your computer,
then use MapSource to create and transfer routes to your zumo.
You can download MapSource here:
https://www8.garmin.com/support/download_details.jsp?id=209I had a 660 several years ago and decided to learn to use BaseCamp since Garmin no longer supports MapSource. This was before I learned of the incompatibility. As the warning states the 660 took the route fine and I started out leading a group of five on a multi-day road trip. After a few miles I got a strange error message - something to the effect of 'there are no roads near your destination' and then the route stopped running. I was able to restart it and it appeared OK for a while but then the same message. After a very frustrating experience I called Garmin when I returned home and learned about the incompatibility.
No problem though. You can open the .gpx file from within MapSource or as Bungy said double click on it and tell the computer operating system to open .gpx files with MapSource and it should open right up.
Hope you get this working for you. Let us know.