1. Key in the function you would like to visualize into the input box.[br]2. You can click and drag on the 3D curve to zoom in and out, or rotate the curve to see it from all sides.[br]3. Use the sliders to change the values of a (x-coordinate) and b (y-coordinate) to see point P move on the surface.[br]4. Use the checkboxes to see the partial derivatives with respect to x and with respect to y.[br]5. Refresh the page if anything goes wrong.