It sounds as though you're using Dreamweaver CS6 or earlier. If you don't have the Structure category in the Insert panel, you won't have the CSS Designer panel either.
The Bayside Beat tutorial is for Dreamweaver CC. If you don't have Dreamweaver CC, you can download a 30-day free trial. Alternatively, follow the six-part tutorial for Dreamweaver CS6, which begins here: http://www.adobe.com/devnet/dreamweaver/articles/first_website_pt1_cs6.edu.html.
Just had a reply from David Powers himself which is kind of him. Apparently it's a different version of Dreamweaver. I was using CS6, in which my only complaint is that the links from CS6 to the 'wrong' webpage didn't explain the options clearly enough.