The Pen tool simulates drawing with a ball-point pen.
To use this tool...
After selecting the colours you with to draw with, click on the Pen button and point the cursor where you want to start drawing. Hold down the left mouse button to draw with the foreground colour; Hold down the right mouse button to draw with the background colour. Begin drawing with the pen by moving the mouse. To change the size and style of the pen, double click on the Pen button.