Well Karl, the problem is that you're wanting to put CMS "into" your existing site, whereas CMS is usually "the" site system. If you haven't looked at Joomla at
http://www.joomla.org or Wordpress at
http://wordpress.com, you might want to give that a once over to see what I mean. They are full website systems where you don't really add them "to" a website, they "are" the website.
There are scripts out there that you can use to utilize editing for sites that give it a type of CMS setup, something like CushyCMS
http://www.cushycms.com/en comes to mind here. Mostly this helps to have people other than yourself to edit the sites.
The main question I guess would be... what about the CMS sites is it that you want to incorporate? If there's a specific thing about CMS sites that you are needing maybe it's something that can be done without CMS. Would need to know more about what it is you're actually trying to learn it for.
The main thing here though is that a CMS is a website rather than a script to add to a website. Hopefully that all made sense