Javascript Cascading Drop Down Menu With 4 Hierarchical Boxes

Hey, so I’m a complete javascript newbie and am trying to create a drop down menu with four different boxes. The site I’m working on is basically an ecommerce site, so I’ll use cars as a good example for what I want to do.

Let’s say that I’m selling cars and want to target the buyer directly, then I would have the following boxes, each one serving as a dependent of the one before it:

  1. Pick the brand (BMW, Mercedes, Etc.)
  2. Pick the type of car (Sports car, SUV, Mini Van, etc.)
  3. Pick the color (blue, green, etc.)
  4. Pick the price ($0-$19,999/$19,999-29,999/etc.)

So far I have the first two boxes down by using the following site: http://www.supertom.com/menugen/example.htm. Now my problem is that the site only allows for the first two boxes to be made, and says that

“the values in box1 are static and printed directly as normal HTML. The corresponding box2 options will also be copied into the HTML as well as the javascript for full functionality.”

Being a complete newbie, I have no idea what this means. So I decided to search the internet for an answer and was not able to find one, thus leading me here, which from the looks of it seems like a great forum.

If anyone could tell me how to connect a third and fourth box that falls into the same hierarchy as the first and the second then I would appreciate.

Really THANK YOU, and I’m really looking forward to reading your replies!!

-Bobby