For digital close-up photography the light is not so important as for 35mm SLR cameras. The white balance could be corrected later, still in some cases maybe as better as preset it in camera. The exposure value is simple to set because of availability of real picture preview in electronic viewfinder, and finally, the amount of light is not so important except if you take photos of movable subjects, on example, small animals. In this case, the macro ring or macro-twin flash will be needed. Most of pictures in gallery part of this homepage was taken at dusk, at low daylight, or was illuminated by common dia-projector.
How to set the lights in practice you can find in the page of Howtodo a bacground.
In this page you can see the differences of lightening directions. I am avoiding to use a built-in flash because it makes unpleasant unnatural shadows.