To get into the basic middle position, start from the basic upper position and get down on your knees, without changing your upper body’s posture. The knees should be slightly wider than the shoulders, shins parallel to each other.
Keep your lower back
naturally arched forward, without strain.
Your hands are behind your back, elbows bent, so, the lower arms are level with the floor.
Bend your wrists, so the back of your hands do not touch. Your wrists should be pressed against your back on each side of your spine. Your elbows should be aimed forward, your shoulders – straightened.
Your chin should be slightly raised, the eyes look straight ahead.

Video demonstration of the basic middle position: