Download Processing from www.processing.org and do some exercises with point() and line(). We are introduced to using coordinates to access pixels on the screen. A coordinate has a X and a Y value. The X value is the distance from the left border of the display. The Y value is the distance from the top border of the display. Using an X,Y pair you can locate any pixel on the screen. The top left pixel is located at 0,0. The pixel at 10,30 is found at 10 pixels from the left border and 30 pixels from the top border.