you can check the Zmapper manual, which explains very clear and easy what normal maps are( you can get it from www.pixologic.com
now there's how to render the normalmap:
for how to set up the shadernetwork, then use ur normalmap for the file needed and I get a very nice result with the maya software renderer.
you can create the normalmap wherever you wish, i suggest Zmapper, it's very fast and you get nice normalmaps ( the surface sampler doesn't work too nice for me in maya and takes loats of time to create the normalmap)
hope that helped a little