To draw a polygon that encloses an area, you need to click on each point around the area you wish to map. As you draw, you will see the distance displayed below the map. When you get to the last point, double-click. This will close the polygon and draw a line back to the beginning. At this point, the area will show up below the map. An important point is that you need to double-click on the last point you want to draw to, not back at the beginning point. If you double-click on the beginning point to close the polygon, there's a good chance that the line will cross over itself and you will not get an area reading.