On the face yes, you just stroke it somewhat firmly. After a few strokes brush the area with your hand or a soft bristle brush as there will be grit from the stone and loose hair, and check your results and repeat if needed
On the top of the head, start at the back of the head and use your free hand to pull the hair forward, so that you are "scraping" the stone on the layer of hair
underneath the top layer. Use very short strokes here, only as long as the hair is