Joomla, Wordpress, Drupal are all CMS "Content management system. They are a dynamically built templating system based off of a very large server side codebase and are database driven. Many large websites use these type of backend as the user interface is pretty friendly and usually requires little code knowledge. There are massive amount of base templates out there for use with those systems.

It is still best to start learning basic concepts of HTML,CSS,Javascript,etc so you will understand exactly how these systems work and use it to it's fullest extent.