The Structure category of the Insert panel is only in Dreamweaver CC, but it's almost identical to the Layout category in CS6. However, if you're trying to follow the How to make and style a web page in Dreamweaver video tutorial series, you will encounter further problems because Dreamweaver CS6 does not have the CSS Designer either.
The video tutorial is exclusive to Dreamweaver CC. If you want a beginner's tutorial for CS6, please follow the six-part written tutorial beginning at http://www.adobe.com/devnet/dreamweaver/articles/first_website_pt1_cs6.html. It uses a different page design, but covers all of the main features you need to get up and running with Dreamweaver CS6.