The Good Morning Squat is considered more of a backwards and forwards exercise, rather than an up and down exercise.
Start with your feet shoulder width apart, and a little away from the wall. Poke your bum backwards until you can just touch the wall without losing balance. What you should feel is a little bit of tension in the hamstrings when you do this.
You keep your back and spine straight, your head in a neutral position, and your knees will bend slightly.