I found some javascript code for drop down menus that are populated based on the value of the one before it, and I'm having a bit of trouble. The code was already writen to have three boxes and it works fine. What I need to do is add one more box to the series. Does anyone know how to do this?...I'm new to JS. The other thing is that the code I found had URL's to all of the items in the third box, I took all of them out and replaced them with my own values, but when I click on a value in the third box it sends me to the parent directory of my site. How do I stop that from happening?
Attached is the code I'm working on. Anything would help, I'm kinda in a jam

Thanks in advance