Adjusting a scope up and down and right and left is called adjusting for elevation and windage. Scopes have elevation and windage turrets. The top turret adjusts the windage -- right to left -- and the turret on the side adjusts your elevation -- up and down. By adjusting the two turrets, you sight your scope in. Sighting in a rifle means that from the distance you sight your scope in, if the cross hairs of the scope are placed in the centre of a target, your shot will hit the centre of that target.
Place the ruler on the paper. Run the top edge of the ruler through the centre of the bull's-eye on a horizontal axis. Make note of the distance of the centre of the bull's-eye from the right side of the paper. Make marks at both the top and bottom of the paper the noted distance from the right edge. Use the edge of the ruler to run a straight line between the two marks. This will be your elevation cue.
Place the edge of the ruler against your straight line. Make note of the distance from the top of the paper to the centre of the bull's eye. On both the right and left sides of the paper, measure down from the top edge and put marks at your noted distance. Use the edge of the ruler to draw a straight line between your two marks. This line will be your windage cue.
Place your rifle on the bench rest in the shooting position. Measure up from the top of your bench rest to the centre of your barrel. Add this number to the distance from the top of your bench rest to the ground. Measure the distance the barrel of your rifle hangs over the bench rest. Measure from your bench rest, down the firing range 100 yards and add the distance your barrel overhangs the rest. Place your straw bale at that distance. Place your paper target at the height of your bench rest, plus the height of the centre of your barrel over the rest.
Take aim and fire three shots into your paper target. Walk to the target with your ruler. From the centre of the three shots, measure to the elevation cue and to the windage cue. Make note of both measurements.
Read the marks on your scope. Each click on the turret will either move your shot 1/4 of a minute or 1/8 of a minute per click. Conveniently, 1/4 of a minute per click equals 1/4-inch right or left or up and down every click at 100 yards. If the centre of your group on the target is one inch to the right of your windage cue, click the top turret left four clicks. If the centre of your group is two inches above the elevation cue, turn the turret eight clicks clockwise. Counterclockwise on the side turret will move your shot up.
Set up your target and shoot three more shots. Check your grouping and make adjustments. Go through this process until the centre of your group is the centre of the target.