@Alen makes a good point, but I think installing WordPress is the way to go if you want to learn WordPress. I had a very, very basic knowledge of HTML and CSS when I started using Drupal. Now I know HTML and CSS way more than before, and I can build Drupal themes and make just about any kind of website with Drupal.
But much respect to Alen, because the truth is, using a CMS won’t teach you anything except how to use a CMS, except I do think it is really good CSS experience. But HTML should be practiced and learned alongside it.