Check your installation CDs for files ending in *.rpm These are
pacakges for the Red Hat Package Manager.
Use your browser and click on the ones that look like they are part of
postgress. It may ask for the root password.
Best thing to do is hit Barnes & Noble or Borders. The books in
question are expensive but you'll save in time
and have a nice desk reference also when you need one. I think it is
actually more common to use MySQL with
PHP but I'm sure Postgres will work fine.