permission denied - Mailing list pgsql-novice

I'm using jdbc to connect tomcat to postgresql.  I a permission denied
when my application tries to acces the database files.
  "/usr/local/pgsql/data/global/1262"
I am trying to change the linux directory's permission, but to who?
    ...postgres
         ...the database user
1. Which one?
2. Do I set permissions using chown and chgrp?
3. Set permission for just 1262 or all in the global directory?

thanks,
Phil