To mount the wheel pants you have to install the brackets. DON"T drill the holes for hte pant at this time. I did and it was hard trying to match drill the hole later. Follow the steps in the plans and you'll drill the hole thru the pant and bracket at the same time when it is lined up.
I put a hole in a square and attached it to the rear of the pant holding it at the exact right height above the ground.