You can use drawing tools to manually trace a bitmap.
Click the Bezier tool.
To start drawing, click in the drawing window.
To stop drawing, press the Spacebar twice.
Click the Pen tool.
To draw a curve, click and drag.
Release the mouse button, and then drag the control handle to create the curve you want.
To finish the line, double-click.
Click the Freehand tool.
To draw, drag in the drawing window.