Begin in basic stance: 
Your feet are positioned directly under your hip bones, parallel to each other, and your weight is centered and distributed evenly over both soles. Your knees are slightly bent (soft), and your pelvis is tucked slightly under (pubic bone toward the navel) in the neutral position. Your ribcage is pulled up out of  your waist; your shoulder blades are pulled together and slightly down the spine. Your neck is long, in extension of your spine.

Head circle:
Think of a horizontal line running under your chin  (for example, a tabletop). Keeping your hips and shoulders lined up above your feet, slide your head across this horizontal line to the right, then push your chin slightly forward. Next slide your head to the left, then pull your head slightly back. Smooth these four points into a horizontal circle that runs parallel to the floor. Keep your face pointing forwards, and keep your body as still as possible. Of course you can also reverse the direction.