web developmen question about CMS instalation

[Siara]

I'm making a web site for a non-profit community organization. It's quite extensive and more time consuming than I'd like. I'd like to put in a user friendly CMS so that other people could handle updating the bulletin boards without having to look at HTML (it's an arts organization and my fellow members are computer phobic). I love the organization but I feel like doing their website is enough of a donation and I'd rather not buy software.

What I visualize is a password protected room where administrators can type new announcements into a box and the system would revise the HTML to include a new table with that announcement.. It would be nice if the new announcement fit in with the rest of the site instead of being in a java-type window, but that's not essential. The server for the site has mySQL, PHP, and Ruby on Rails. It seems like there's a lot of freeware that I could use to potentially do this job, but the documentation is incomprehensible to me. I need something that says "put this script in that folder" or whatever, as if it were giving directions to a baby.

Can anyone recommend any freeware with Documentation-for-Dummies or an easy to understand book on this subject?

I considered doing it with a blog but, in spite of claiming to have visually adjustable formats, the freebie blog sites seem to have large company logos, pop up ads, and/or a set of options that result in a very chique, space-age (to me ugly) look.

Edited April 25, 2009 by Siara