You have learned some new terms and concepts in CSS.  If you don't understand the ones listed below you should go back and do the tutorial again!  You don't need to remember it all but you do need to understand it when you read it:

If you remembered all that well done.  You still need to practise though to be sure you retain all the skills you have learned,  That comes next.

If CSS ever fails to work try the W3C validator for CSS.  It works much like the HTML one but just paste in the CSS not any HTML.