This is a pretty good tutorial for doing the installation manually.
http://www.phpfreaks.com/tutorials/12/0.php
RH9 comes with RPM's for everything you need if you just want to have a local development server and have no interest in compiling from source.
You can actually use the Services applet in RH9 to start the httpd and mysqld services manually or configure them to automatically start for your runlevel. Once you've installed the RPM and started httpd, you should be able to hit
http://localhost and get the default installation page. If you have difficulties accessing from remote machines just remember the default install of RH9 has a full firewall enabled.
If you want to learn how to configure Apache, PHP, MySQL from source then this tutorial will get you to the point where you'll be comfortable enough with the process that you can then use the installation instructions from
http://apache.org/,
http://php.net, and
http://mysql.com.
Hope this helps,
Mike