Why doesn't import work?

[ssecorp]

I have in Lib/site-packages a module named pdfminer. when I do import
pdfminer it complains:

>>> import pdfminer

Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    import pdfminer
ImportError: No module named pdfminer


I created a file pdfminer.py and put it in site-packages and that
works.

so I apparently can't import a directory pdfminer. In the directory
pdfminer there are 3 other directoriees and inside them python-files.

how would I import them?