Attaching a Python library?

How do I attach a python library?  I'm using the Google App Engine and I tried adding its zip file as a Global Library (as a "Classes..." jar) but I still get an "Unresolved reference" error.  So I unzipped it and made a module out of it and got a little further, but now in the following snippet the second 'webapp' is unresolved:

from google.appengine.ext import webapp

class MainHandler(webapp.RequestHandler):