New User - options and other "get going" questions.

Hi,
   I have just installed the lastest PostGreSQL version as an RPM.  I am
using the /etc/init.d/postgresql file provided to start and stop. I am not
that conversant with shell programming (YET).

   I want to keep tables in "/rwhdata2/data" rather than
/var/lib/pgsql/data".  I presume that $PGDATA is set to
"/var/lib/pgsql/data", but I can't find out where.

   Typing "echo $PGDATA" logged in as either root or postgres returns a
blank line.  Can someone point me in the right direction.  I have three
books on my desk that purport to explain Postgresql and they all mention
PGDATA but none clearly delineate where it is set.

   Thanks,

Bob

Please reply directly as I am not sure that I am getting any list traffic
even though I checked to receive all messages when I subscribed.  Thanks!