Light Photography with a Nikon D80?

If it's possible, what are the settings to use for light photography with a nikon d80?

ALL photography is light photography. That is what cameras do, record the light falling on the subject.

Do you mean shooting light graffiti?

To do that, you just need a tripod and use the bulb setting on the camera. A remote release will prevent camera movement which could be evident if you use your finger to hold open the shutter release for a few minutes