Ideally you should have an existing site which has been defined within Dreamweaver, and is connected to a server. (I normally have a 'test' site where I try out CSS and other advanced techniques. This avoids corrupting an existing site).
Make sure the Insert panel is visible above the main work area (WINDOW...Insert) and click on the Spry tab:
This menu bar offers options such as Data Sets, seven additions to forms such as entry validation, password validation etc. The final five icons allow you to add more interactive elements to your web page: