Here's the simplest way I can explain it... With a picture!
We teach a LOT of people how to shoot primitive bows when we give demonstrations at Civil War Reenactments (Civilian Archer's Society), and when we do, we teach the "gap shooting" method.
If you want, you can get Byron Ferguson's book "Become the arrow," or just read my synopsis below, combined with the picture of one of our ladies shooting her bow. (blue line is sight line, red line is flight path of the arrow)
Building the shot from the ground up
Stance
Stand 90° away from the target with the left side of your body facing the target. Stand with your feet about shoulder width apart with most of your weight on your left foot , this will cause you to lean just a bit towards the target
Grip
With the bow in your left hand, use your right hand to take an arrow by the nock and place it on the left side of the bow on top of your knuckles.
The arrow will ride on top of your left knuckle – do not extend your left index finger or the fletchings may cut you, you should grip the bow firmly, but not a with death grip. Think of the way you would grip a mop or a broom handle and hold the bow similarly
Place the arrow on the string at a 90° angle to the bow with the odd colored feather facing out
Place your index, middle, and ring fingers of your right hand on the string with the arrow between your index and middle fingers (this is called a “split fingered grip”
Tilt the bow about 45° to the right
Draw
Since the bow is tilted 45° to the right, the fletchings of the arrow will form a “V” with the upper two feathers, bring this back smoothly, and directly under the pupil of your right eye
Your right middle finger must find an anchor point on your face – that is – a reference point (such as the corner of your mouth) that you draw to so that each shot is consistent
Aiming
Aiming is just a short pause before loosing. Your focus is ALWAYS at the target – the arrow is just seen in your peripheral vision. And don’t just focus on the bullseye itself, try to focus on the fly that just landed on the center of the bullseye – remember, “aim small, miss small!”
Windage - As the arrow is drawn directly under the right eye, sight along its length, and draw an imaginary line straight to the bullseye
If your shots pull to the left with the arrow lined up straight to the target, try rotating the bow more to the right, and your shots will move right
Elevation – To gauge the elevation of your shot, you will do what is called “gap shooting.” When the arrow is drawn under the right eye, in your peripheral vision, you will see that there is a gap between the tip of the arrow and the bullseye. By taking a few test shots, you will be able to measure what this gap should be to hit the bullseye
The closer you are, the lower on the target the tip of the arrow will have to be
The farther you are, the higher on the target you will have to be
With practice, this will become second nature
Loose
To loose the arrow, simply relax the right side of your body. You will know that you have done this correctly when your right hand travels backwards near your right shoulder