Boom. My first Processing sketch uploaded to the website. Took a few hours, but I finally figured it out.
Click anywhere in the sketch to begin drawing lines. The line will follow your cursor and then be finalized when you click again. If you mouse over the end points, the circle gets large. Next step is to add deletion and re-positioning functions.
NOTE: Java applets are on their way out of the interwebs. This may not work in your browser. Sorry!