CSS stands for Cascading Style Sheets. While HTML gives a page its structure, CSS is the look and feel of that page. Any page can be styled in an infinite number of ways, giving web designers and developers infinite flexibility in their designs.
There are many ways to create navigation for a website. CSS is one of the most common ways. In this screencast, Scott demonstrates the basics of creating navigation from a list of links. This is the first of two videos. Screencast #2 finishes this demonstration by showing how to finish the navigation. The second screencast also deals with how to divide a page into sections (called "includes") for streamling a page in PHP.
This is the first in a series of screencasts. The other videos can be found in the dropdown menu at the top of this site.