PHP form question

Its been a while since I have been here. Glad to see kirupa is alive and well.

TIME IS OF THE ESSENCE!!! The owner is waiting on me for this and is putting a lot of pressure on me. Any help would be greatly appreciated.

my question is regarding a php / mysql form I am trying to update. bear in mind that I am somewhat of a noob using php / mysql. I did not create the website. I maintain as best I can.

I am trying to update a form made using php. you can view the form here.
http://www.vutec.com/repfinder/

the form is dynamic I believe. reason I write this is because, depending on what country you choose from the COUNTRY drop down menu, determines what options appear in the form below.
for example, if you choose CANADA from the drop down menu the ZIP CODE and STATE radio buttons disappear, the PROVINCE drop down menu appears, etc…

my question is this. how do I make changes to the form after choosing CANADA from the drop down menu? changes I need to make are;

  1. replace SEARCH REPS button with a DISTRIBUTORS button.
  2. remove home theater and commercial radio buttons.

THANK YOU ALL.