Drawing Curves, Freehand.
Using either a pencil or your brush (and we can safely assume a stick of pastel or a marker or even a loop tool would be acceptable substitutes, depending on your medium of preference,) rest the part of your hand beneath the pinkie on the support. Use your hand like a compass--with the point of your hand that touches the paper being the center and the tip of the pencil to that point being the curve/arc/circle's radius) and use a pivoting/rotary motion to:
First--hover above the paper (or other support) and "practice;"
and then--lower the tool to the paper and lightly put down that curve. Useful to know if you have to draw or paint these: