Newbie question

[Jive Dadson]

I am completely new to Python.  This is probably a stupid question, so please humor me.

I have two Python books, _Core Python Programming_ by Chun and _Python and Tkinter _Programming_ by Grayson.  I also downloaded a trial copy of the Wing IDE.  After correcting some indentation errors, I have been able to run the first example in Grayson's book, calc1.py.  But when I try to run calc2.py, it complains that it cannot find the modudle Pmw.  Pmw stands for Python Meta-widgets.  The Core Python Programming book seems to indicate that Python needs to find a file called Pmw.py (page 384, section 12.2).  But when I search for the file, I can't find it.  I find dozens of related files, with names like pmw_labeled_widget.py and PmwButtonBox.py, but there appears to be no plain vanilla Pmw.py.

So there are two questions really: 1) If anyone has used the examples out of _Python and Tkinter Programming_, how did you do it? ... and 2) Is there a web page or something that explains everything I need to know about how Python finds modules?

Best regards,
Jive