The Data Assist and Security Assist wizards will automatically generate PHP pages with the functionality.
If your design is a Dreamweaver Template, you can apply the temptable to the pages after they are created, Modify -> Tempaltes -> Apply Templates.
if you are not using a template for the design, then you have 2 options:
1) Use Framework builder to add the pages created by the wizard to your existing designed pages as a plugin
2) Create the functionality manually in your design pages rather than use the wizards. at the end of the day, the wizard just creates pages with forms on them, then adds the appropriate server behaviors for authenticating the user or manipulating the data base.
all of the Web Assist server behaviors can be accessed from the server behaviors panel, click the plus button and browse the Web Assist menu.