You will need the psycopg2 package for Python for the materials here, as well as access to a PostgreSQL server. The examples here use the database from the PostgreSQL Tutorial.
SQLAlchemy: another Python library used extensively by developers. There's a steep learning curve for this library (at least for the advanced features), but if you'll be doing a lot of database work from Python, it's worth a look.
Guide to SQLite in Python: If you want to try SQLite instead (a good option if you're working on a project on your own with a relatively small database), here's a place to start.