I don't know anything about map source so I can't help there sadly. I found Memory Map was easy enough to use. You simply 'draw' your route, right click on it and click the 'Export to GPS' option.
You then look on Routes on the menu and there it is. You then push in the joystick and it is on the screen. You then have to option of viewing each section. For Example you get a compass in the middle of the screen directing you to your next waypoint. Then in the boxes at the top of the screen you can have a range of option; Average Speed, Odometer, ETA,Elevation, Current Speed, Distance to next waypoint and some others. Or you can view it in a birds eye view style with the current point you are on, the next point and the point you are going to. I use the compass layout as I know where I have been.
Hope this sort of helps..