Newbie question - Creating a new face

I’m trying to build a script that builds stairs (It’s my first script) in order to learn the scripting system, and I’ve run into a bit of a problem:

How do I add a new face to the mesh?

I create an Object, then an NMesh. The documentation shows how to create a vertex, but it doesn’t give any details on creating complete faces.

I’m using Blender 2.4, if that matters…

A nice tutorial by jms (first hit on google when you search on: blender python tutorial).