To start press the green flag, then click on the colorful circles to select what color you want to draw with. You can also click the keys b (for blue) g (for green) r (for red) and y (for yellow) on you computer to change to color of your pens. You can click the eraser and change the size at the top, to eraser parts of your drawings, or click the X to erase them all. Or you can click the c key on your computer to clear all of your drawings. Lastly, you can click the right arrow to increase the width of the pencils, or click the left arrow to decrease the width.
Raspberry 1.5 Paint Box Tutorial