Karin Wells did a great topic on Rembrandt lighting in another section of this forum. I will try to find it and post the URL.
Here it is:
http://forum.portraitartist.com/show...s=&threadid=56
I am assuming that you want the lighting setup to illuminate a model yes?
The basic concept of Rembrandt lighting is one high raking light source at about a 45 degree angle from the object or person you are lighting. You need some sort of reflection device on the other side to bounce a bit of light back into the shadow areas - I use a piece of white mat board.