In the top left corner, there should be logo of some sort. Below that, there should be the graph window, and below that, the text box where you put in the equation.
You put in the equation, and then click the "Go" button. The graph is drawn on the graph window. The x and y bounds are defaulted to -10 to 10, but when you tell it to graph, it finds the maximum and minimum on the x range and then sets the y range accordingly (ie, minY is the minimum - `10%, and maxY is the max + ~10%.) Then, it takes the integral and shows the boxes it made to do that. The options are going to be right sum, left sum, middle, Simpson's rule, and trapezoid. You will be able to pick with buttons below the input box.