Initdb problem in red Hat 6.0

Hi,
    I am a cs student at BYUH.I am trying to install Postgresql 6.5.2.1 in my Red hat linux 6.0. After the RPM
installation,when I try to initdb.   I always got a masseage like  
    initdb does not know where to find the files that make up
Postgres (the PGLIB directory).  You must identify the PGLIB
directory either with a --pglib invocation option, or by
setting the PGLIB environment variable, or by having a program
called 'postconfig' in your search path that outputs an asignment
for PGLIB.
I tryed this "/etc/rc.d/init.d/postgresql start"
also. It give me a message like
    We are initializing the database system with username postgres (uid=40).
This user will own all the files and must also own the server process.

rm: cannot remove `/var/lib/pgsql/base/template1': Permission denied
mkdir: cannot make directory `/var/lib/pgsql/base/template1': Permission denied
Creating template database in /var/lib/pgsql/base/template1
Starting postgresql service: /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.

Can you help me find out what is the problem.
THANK YOU