I wasn’t overly happy with the way that this was shown on W3Schools. The navigation bar and dropdowns were on different pages and it wasn’t till you got to the end that you saw how it worked. Even then the sub page links were not held in a sub list they were displayed in a div.

I found this article, which gives a good explination (along with samples) of how you could create a multilevel naviational bar that uses lists. The code is quite complicated and it relies on element element selector.