How to cut hair back of the head concave #3 back of head versatile concave cut

How to make a back of the head versatile concave cut:
I should have said why you need to cut the back of the hair high concave cut and don’t cut the front hair line at all.
Long hair
She had very long hair to begin with, I just cut the hair still quite long hair, back of hair is still very heavy and long, hair is hardly move at all, just hang on,
if I cut back of the hair all layer, then hair will be too light and too messy looks, I need hair to move and still soft, that why I did back of hair made a concave cut line, hair is still has volume and when wind blows, the hair will move nicely