You should now understand the principles of HTML:

CSS is the way to fix the last point and soon you will learn how but first...

Practise and checking

Like any skill you need to practise HTML over and over until it becomes easy.  To do that you need four main things:

  1. an understanding of the principles from this tutorial (so go back and do some bits again now if necessary)
  2. ideas of Web sites you could create (mostly down to you but one idea is coming up)
  3. the ability to find more information on specific topics by searching
  4. a way to check that your code is right