You probably need to learn much more about both then.
O'reilly also makes books on all of these subjects, the DBI book, and the Postgres book are good starting places. Caveat: The postgres book is out of date, the Postgre doc package can largely replace it. Read up on:

1. Linux
2. Postgre SQL
3. DBI (Perl database framework)
4. DBD::Pg (Postgrase database driver for DBI)