Forget holding the rifle on target while trying to adjust, just look at the target to see which way the group needs to move to center it to your point of aim. Hence the only time trying to hold the rifle on the target while adjusting the scope works, is when you have a second set of cross hairs in the rifle that you can hold the first set on our POI, adjust the seconds one over to the group (so you can check to make sure that the first sets in on the center of the target, the second in the center of the group), then you adjust the first set over to the second set instead. So again, three shot on the target, see what way the bullet need to move to get them back to center, then adjust the scope via clicks.
The scopes adjustment direction are labeled backwards if you are thinking that is the way the cross hair will move toward the target. They are not , and the arrows/directions are if you are moving the bullets impact to the center of target instead. So look at the target, measure the distance that the bullet had to move to get to the center of the target, and adjust the scope as if your moving the bullet impact on the target. If the group needs to be more up to center on the target, then adjust the scope in the up direction markings on the scope!!!!! If the group needs to be more left to center the group on the target, then adjust the scope in the left direction markings on the scope.
MOA is 1" at 100 yards.
The scope adjustments are either 1/4" MOA, or 1/8" MOA.
If the scope is 1/4" moa adjustment, then at 100 yards, each click of the scope adjustments will move the group 1/4" in the direction of the arrows on the scope.
So since we now that the adjusts per click of the scope is at 100 yards (MOA), that lets take the 1/4"scope adjustment, and use that for a few different yardages.
At 50 yards, one click of the scope adjustment will move the group 1/8".
At 100 yards, one click of the scope adjustment will move the group 1/4"
At 200 yards, one click on the scope adjustment will move the group 1/2"
At 300 yards, one click of the scope adjustment will move the group 3/4"
At 400 yards, one click of the scope adjustment will move the group 1".
So your multiplier is the Minute of angle for 100 yards, and as the distance gets farther, the times that by the yard to figure out how much a MOA adjustment is going to move the aim of the scope per adjustment click.
http://bulletin.accurateshooter.com/2014/12/understanding-minutes-of-angle-moa-intro-video/