What is concrete5?
concrete5 is an content management system for your website. It is very easy to use and allows you to edit your website content directly on the page and not in some complicated backend. So you can see your changes as you make them. Free and open source, concrete5 is used by everyone from personal websites to the US Army, you can try it at concrete5.org.
If you are looking for an alternative, a great option is WordPress; check out some WordPress guides and resources at FusePage.