Put your camera on a tripod, focus it, then set it to a long shutter speed. Turn off the lights. Click the picture. While the shutter is open shine a small flashlight or pen light over the subject. Stop when you think it's bright enough. There is no way to instruct how to do this part, it really is experimental.
If you try this technique tell me in the comments. I'd love to see what other people do with it.