How to Install NagiosQL
Configuration of Nagios can be very daunting task but can be made a little easier with using NagiosQL from http://www.nagiosql.org
Some requirements are MySQL, PHP 5.2 or better
If you dont have MySQL server running install it.
yum install mysql
yum install mysql-server
yum install mysql-devel
Create MySQL password
/usr/bin/mysqladmin -u root password 'somepasswordinhere'
Need Pear (check to make sure you have all requiremets)
yum install php-pear
pear install HTML_Template_IT
If you need to upgrade PHP to higher then 5.2 http://www.mrbuckykat.com/howto-upgrade-php-5-1-to-5-2/
From here check out this good post from Awalrath at http://aaronwalrath.wordpress.com/2010/02/28/installing-nagiosql-3-on-centos-linux-5-4/