Well for a start to make an ellipse appear like a ball you need to make a CIRCLE not an ellipse, then depending on the angle of the light you need to do some VERY basic lighting algorithms ASSUMING the object IS 3 dimensional. If you set the light source to be pointing through the centre of the circle and its angle varying as it travels around the shape then the lighting shouldnt be too hard to figure out. What output do you have at the moment?