Wordpress is one of the blogging platform kings. But it can also be turned into a powerful CMS capable of controlling all the content of your website. There are many valuable resources freely available on the Internet that can teach you how build your own Wordpress theme from a PSD mock-up design. One of wordpress' main attractions are its' numerous user generated plugins that can save a lot of time when trying to implement a star rating system or a "share this article" social media icon banner. Wordpress is also known for it's great SEO compliant markup and has plugins for optimized Search Engine Optimization of your pages.
Wordpress is easy to use once you get used to it (I built my first Wordpress website last week) and can bring a lot of functionality to your pages.
Joomla is among the most preferred CMS because of it's "extentions" which are essentially the same thing as plugins for Wordpress, just under a different name. Joomla has very good documentation on how to get started with their system.
Drupal is another well known and widely used CMS. Because of it's extensive use to build websites, a lot of free content is available for reference when building a Drupal theme.
CushyCMS is also a CMS application, and it very easy to implement. The application simply let's you add a class item to your xhtml tags and makes the content editable from the website's control panel after you log in.
Try one out, I'd recommend Wordpress for a first time as a lot of blogs have answers to troubleshooting questions, and their documentation isn't bad either. You can try building your own theme using WAMP that I mentioned in a previous post.