How to light paint with Nikon D3100?

Details Please.

I have a Canon, but your Nikon should have a "bulb" keeping the shutter opened until you choose to close it… Usually with a manual shutter control or timer in the camera. Basically you have to open the shutter in the dark, "paint" the air with a light stick or flash light in the proper frame, then close the shutter. It will take experimentation to know how long to make your exposure, but it will most likely be in the 3-5 second range if it is dark enough in your environment. The images you get will have to be post processed in an image editing program to maximize and tweak your results.