The Freehand tool is great for drawing curves, but sometimes you want to create a curve by placing specific points in specific locations. For this task, the Add Points tool (A) is what you want to use. With the Add Points tool, you can click in the working area to place points, and the curve that is created runs smoothly through these various points.
To create a curve with the Add Points tool, click at the location of the first point and then drag to the location of the second point and release the mouse button. If you click again after releasing the mouse button, you can drag to place another point that will be attached to the curve. If you move the mouse cursor after creating a point, then a new curve is started.