Mod_Python - How to make Publisher Handler work?

[Nancy]

Hi,
  I follow the Mod_python manual and try to let my form.py to handle
html form. The form.html and form.py are copied from
http://www.modpython.org/live/current/doc-html/tut-pub.html,
after I click "submit", it always calls the page of 'Hello World',
that is myscript.py:
  from mod_python import apache

  def handler(req):
    req.write("Hello World!")
    return apache.OK

  Where is wrong?
  Who knows where I can get a more basic and simple tutorial about
mod_python?
  Thanks a lot

Nancy