You can create a Bezier mask using the Pen tool on a selected layer in the Composition panel or Layer panel. You can create a shape with a Bezier path using the Pen tool on a selected shape layer in the Composition panel. If you draw with the Pen tool in the Composition panel with no layer selected, you create a shape on a new shape layer.
Creating a RotoBezier path is similar to creating a manual Bezier path. The primary difference is that direction lines for vertices and curvature for path segments are automatically calculated.
Create a manual Bezier path using the Pen tool
Draw straight manual Bezier path segments with the Pen toolThe simplest path that you can draw with the Pen tool is a straight line, made by clicking with the Pen tool to create two vertices. By continuing to click, you create a path made of straight line segments connected by corner points.

Draw curved manual Bezier path segments with the Pen toolYou create a curved path segment by dragging direction lines. The length and direction of the direction lines determine the shape of the curve.
Shift-drag
to constrain the angle of the direction lines to whole multiples
of 45°. Alt-drag (Windows) or Option-drag (Mac OS) to modify only
the outgoing direction line.