The entire purpose is to control the cow. You have to do certain movements and then they will whistle you off the cow. Everyone starts off with 70. Depending on the quality of your run, you'll get + or - on certain maneuvers which determines your score.
You have to "box" the cow on the one end of the area 1st - so move it back and forth and keep control and in position while working it (there is an optimum position you need to be in to control the cow - if you are out of position, the cow can get away from you).
Then you have to drive it around the corner to take it down the fence. You'll see the PERFECT position for doing this in Doug's Video - his horses shoulder is at the hip the cow.
Once moving the cow down the fence, you must stay in position until you go to turn it - so keeping the horses shoulder about at the hip of the cow and you want to be close. If you are too wide, the cow can stop and turn before you do. Once you pass the center marker, you move up on the cow to cause it to turn. You want to be close so that you can come out of the turn and be right there to drive it down the fence the other way. You need to do at least two turns on the fence - one each way.
driving down the fence:
(not sure who this is)
Credit earning turn:
Not a credit earning, maybe even a minus since he's far away from the cow on the turn (don't know who these are):
After you turn the cow on the fence, you then have to take it off the fence and circle it both ways. You want your horses shoulder by the cow's shoulder so you can turn it in a small circle.
A little far away but not bad.
(These are pix that I took, fyi)