If you need to access an Oracle database using python (actually, to access any database), the first thing you'll need to read is the Python Database API Specification 2.0, which proposes a standard interface to be used by database access libraries. This specification is database agnostic, and various libraries exist which implement it (more or less strictly) for different DBMS.
The library I am using for Oracle access is cx-Oracle, which (almost!) conforms to this specification.
If the Python Database API Specification is too abstract for you and you'd be happy if the official cx-Oracle docs contained more examples, what you need is a nice tutorial to introduce yourself to this library. Then maybe another tutorial to go beyond the basics. Now probably the Specification and the cx-Oracle docs make more sense!
Oh, if you want to work with cx-oracle, you will need to install it first :-). I found very useful this howto by Catherine Devlin. If you work with Ubuntu, you will love it for sure.
Hope this helps!
PS
I assume that yo have some familiarity with Python and Oracle.
If not, I bet this post is not the most interesting you've ever read!
