How to do stair trails on D50?

For my media project I've decided on doing stair trails, I will be using a Nikon D50
I was wondering what iso I'll need it on and f stop too, I know to used the bulb setting with tape to stick down the shutter
You can suggest anything else to get best results if you want
Cheers

ISO should be as low as possible - 100 or 200

Aperture should be around f4

Exposure time will depend on ambient light - if it's bright where you are, you may get overexposed skies.

Check battery power too - you will also get the sensor heating up much past a minute or so, won't damage it but will cause 'noise'.

Better to do 30sec individual shots (several hundred) & stack them if you want trails - this is good freeware;
http://www.startrails.de/html/software.html

Oh btw, "tape to stick down the shutter" - sounds like a recipe for serious camera shake. Suggest you get a remote release.

For exposures of 30 seconds or less you can use the camera's self-timer. For longer exposures you should use the Nikon ML-L3 Wireless Remote. Of course your camera has to be on a tripod.

This gives a good explanation of how to do star trails.
http://www.danheller.com/star-trails

Http://keerok-potd.blogspot.com/2011/12/more-star-trails.html

The camera you're using doesn't matter. The principles are the same. You'll have to experiment to see which settings are right. I'd start with ISO 100, f/5.6, 5 minutes. Then adjust from there. You may have to do long exposure noise reduction because you WILL get noise from a long exposure. Make sure your tripod is solid and is on solid ground.