The PostgreSQL distribution contains a comprehensive documentation set, which you should read sometime. After installation, the documentation can be accessed by pointing your browser to /usr/local/pgsql/doc/html/index.html, unless you changed the installation directories.

The first few chapters of the main documentation are the Tutorial, which should be your first reading if you are completely new to SQL databases. If you are familiar with database concepts then you want to proceed with part on server administration, which contains information about how to set up the database server, database users, and authentication.

Usually, you will want to modify your computer so that it will automatically start the database server whenever it boots. Some suggestions for this are in the documentation.

Run the regression tests against the installed server (using make installcheck). If you didn't run the tests before installation, you should definitely do it now. This is also explained in the documentation.

By default, PostgreSQL is configured to run on minimal hardware. This allows it to start up with almost any hardware configuration. The default configuration is, however, not designed for optimum performance. To achieve optimum performance, several server parameters must be adjusted, the two most common being shared_buffers and work_mem. Other parameters mentioned in the documentation also affect performance.