Draws individual lines or points. Wait until you see a row of buttons ( red , green , blue ... ) followed ( Lines ). Click on any of the colored button to set the color of the lines/points to be drawn. For drawing lines, left-click at the starting point of a line, move the mouse-cursor with left-button depressed until endpoint of the line is found. For points, simply left-click at position of point ( it'll be very small, barely visible ). You can toggle back and forth between points, lines and between different colors.