How to code buttons with drop down and sub drop down menus?

[codecanbecool]

I am using Dreamweaver CS5 and I am coding a site which is still under construction, in HTML and CSS. I have created several buttons and positioned them. Tested them in my browser and everything is running smoothly. However, my client has just come back to me and has asked for some of these buttons to drop down when hovered over. At the moment they only change colour when you hover over. How and what coding do I add to these individual buttons in order to get a drop down and in some cases, a sub-drop-down menu/s?

here is a link to the buttons I want on my site within my navigation bar:

buttongenerator.com/

Thank you!

[riptide]

Make your own buttons so you can have better control over them. I don't trust
buttongenerator to use good coding, the site it's self is using tables for layout.

[david_deseine]

Jquery library is IMO a good solution, just Google jquery menu drop down.