This manual set is organized into several parts:
An introduction for new users. Does not cover advanced features.
Documents the SQL query language environment, including data types and functions.
Advanced information for application programmers. Topics include type and function extensibility, library interfaces, and application design issues.
Installation and server management information
Reference pages for SQL command syntax and client and server programs
Information for Postgres developers. This is intended for those who are contributing to the Postgres project; application development information should appear in the Programmer's Guide.
In addition to this manual set, there are other resources to help you with Postgres installation and use:
The Reference Manual's pages in the traditional Unix man format.
Frequently Asked Questions (FAQ) lists document both general issues and some platform-specific issues.
README files are available for some contributed packages.
The PostgreSQL web site carries details on the latest release, upcoming features, and other information to make your work or play with PostgreSQL more productive.
The <pgsql-general@postgresql.org> (archive) mailing list is a good place to have user questions answered. Other mailing lists are available; consult the User's Lounge section of the PostgreSQL web site for details.
PostgreSQL is an open source effort. As such, it depends on the user community for ongoing support. As you begin to use PostgreSQL, you will rely on others for help, either through the documentation or through the mailing lists. Consider contributing your knowledge back. If you learn something which is not in the documentation, write it up and contribute it. If you add features to the code, contribute it.
Even those without a lot of experience can provide corrections and minor changes in the documentation, and that is a good way to start. The <pgsql-docs@postgresql.org> (archive) mailing list is the place to get going.