Lie on your back with your knees bent and your feet on the ground to allow for a flat lower back
Place the peanut tool under the base of your skull and lie back down
Gently nod your head while the peanut tool is on the tender spot of the neck.
Using a yoga block helps keep the head in a position which makes the movement easier and more effective
Guia do Exercício Laying Cervical Extensor Mobilisation Peanut Tool | MuscleWiki