Trigering PHP Code

Hello All,
I have two problem in my php file i.e.

1. I want to triger some php code, soon  after when a selection
is done from Drop Down Menu,
For Example:
When user select country name the State,city menu fill dynamically.

2. I want to use a variable value gathered in one php file to some any
other php file

For Example:
When user enter his/her name , I will use in later processing in by
some other php file.

I hope, I have explained my problem:

TIA,

Regards,

--
Nayyar Ahmad

Lecturer
Faculty Of Computer Science,
Institute Of Management Sciences,
Hayat Abad Peshawar , Pakistan.
Office : 92-091-9217404 , 9217452
Cell     :  92-0333-9139461