I went to the following url http://www.ghacks.net/2009/06/08/how-to-install-nagios-on-ubuntu-server from searching google. however the urls referenced were actually no longer good. So i used the ones below from same site. I downloaded the files
http://sourceforge.net/projects/nagios/files/nagios-3.x/nagios-3.2.3/nagios-3.2.3-tar.gz/download?use_mirror=cdnetworks-us-2
http://download.sourceforge.net/project/nagiosplug/nagioplug/1.4.15/nagios-plugins-1.4.15.tar.gz?r=http%3A%2F%2Fsourceforge.net%2Fprojects%2Fnagiosplug%2F7ts=1304724053&use_mirror=voxel.
I then typed ls and found a directory for nagios-3.2.3 and also the plugins. How do i get the ngaios files and the plugin to install so I can run them? I am a bit new to ubuntu. Sorry if this is a bunch. Thanks for your expertise.