Hello!

I don't know if there is the right place to ask my question. If not, please
accept my apology.

I'm totally new to Linux. And I have troubles using the PostgreSQL.

I installed Redhat 6.0 and find there is postgresql already installed on my
computer.
Running the following command I get:
////////////////////////////////////////////////////
$rpm -ql postgresql
/etc/rc.d/init.d/postgresql
/usr/bin/cleardbdir
/usr/bin/createdb
/usr/bin/createuser
/usr/bin/destroydb
/usr/bin/destroyuser
/usr/bin/initdb
/usr/bin/initlocation
/usr/bin/pg_passwd
/usr/bin/pg_version
/usr/bin/postgres
/usr/bin/postmaster
/usr/doc/postgresql-6.4.2
.....
(All the /usr/doc entried are omitted here since they are too many)
......
/var/lib/pgsql
///////////////////////////////////////////

I thought it's ok to start the postgresql server, so I run the following
command but it complains:
(the command was found in the "/etc/rc.d/init.d/postgresql" file)
//////////////////////////////////////////////
$postmaster -i -D/var/lib/pgsql
/usr/bin/postmaster does not find the database system. Expected to find it
in the PGDATA directory "/var/lib/pgsql", but unable to open file with
pathname "/var/lib/pgsql/base/template1/pg_class".

No data directory -- can't proceed.
////////////////////////////////////////////

I read the installation instruction of the PostgreSQL but it teaches you how
to install from the beginning and expect you to use the file
"postgresql-v6.4.tar.gz", which I haven't got on my computer.

I also tried to run the following command:
$initdb
but it cannot work yet.

Someone told me I should establish a data store for the PostgreSQL. What's
that? How to?

Do I need to download "postgresql-v6.4.tar.gz" to re-install the PostgreSQL?
Or how can I
solve my problem? What's in the earth wrong? What's indeed the PGDATA mean?

Any suggestion or hints are appreciated greatly!

With my best regard:
Janet