1) Download area under curve.xml and sketchpad.jar.The files can also be found at the bottom of the page.
2) Double click on sketchpad.jar to run the programme.
3) Open the file area under curve.xml
4) Select the equation y=e^(x/5) and the click on "Area"
5) You can make the rectangles start from the right by unchecking the "Starts from Left?".
6) You can also increase the number of rectangles.
7) You can also use trapeziums instead of rectangles.