Do I perhaps need software that did not come with the Garmin Map 60 CSX? Mapsource?

I have the .gpx file downloaded, my gps connected to the computer, but cannot open the file or see how to transfer it to the gps unit. Any help?

I just joined Hike Arizona, as I found the group while researching a place to take a backpacking trip with my girlfriend's 13 year old son. Since I've been lost overnight in the wilderness before, I am really concerned about that ever happening again. I have a Garmin GPS Map 60CSX that I've only use...