Are you referring to "Star Trails"? If so, there are several good "how to" videos on YouTube on how to do it. One can be found
here
"Light pollution" must be ZERO. A cold, clear and moonless night is ideal. I set my ISO on 1250 and find the North Star. All stars rotate around the North Star, or Polaris. I set up the camera to take about 150 - 30 second exposures @ f/5.6 but you may need to tweak it for your area. The easiest way I have found to do this, even though the D700 has a built in intervalometers, is to set the camera on Continous (High) and use a remote shutter release to lock open the shutter. As soon as the shutter closes, it will cycle again and the shutter will open again for another 30 seconds, and so on and so on. You can use something light Lightroom to tweak one image, getting the blacks as deep as possible, and then synching all of the images.
I use a program called StarStax and it works perfectly. Make sure you select "gap filling" when you set it up. Also, if you are out on a cold night, remember that your batteries will not last you as long as they normally would. Have a spare set ready to go. DO NOT move the camera when changing the batteries or all will be lost and you will have to start over. It is far easier to change the batteries in a grip then it is to open up the door on the underside of the camera.