As mentioned already, Blogger is the simplest way to get something up and running as you don’t have to install anything on your own website. You only need FTP-access to your own site to have blogger publish your pages on your own domain. And Blogger is free. If you are on a windows machine you can use wBloggar, this is a stand-alone program that let you publish stuff with blogger without the need to actually log into the blogger-site.
If you want something more powerfull and you can run stuff (like PHP and MySQL) on your own website then I recommend Geeklog (www.geeklog.net). I have several sites running on Geeklog (including my company website) and it is very robust software. It’s also Open Source so it’s freely available. And with Geeklog you don’t need any other software, all editing is done inside your own website.
You can also visit www.opensourcecms.com as they have several systems available online for you to play with and try out.