An overlooked use of your GPS.
Sorry you're off to a not so smooth start with Garmin. I've been told that some of the new units require the purchase of some software right up front. Too bad the clerk did not make you aware of this.
Here's a tip on a way that you can use your GPS:
When I get a long shot at an animal, I mark the spot from where I shot as a waypoint. Then I walk to the downed game and, from that spot, I ask my GPS to tell me how far I am from the shooting waypoint. It gives the distance in 1/100ths of a mile. Just convert that to yards: multiply 17.6 x (number of hundredths) For example, your GPS shows that you are .16m from the waypoint from which you took your shot, so multiply 17.6 x 16 = 281.6. Conratulations, you just shot a deer (or whatever) from 282 yards. Nice shot!