Is it possible to change submit button's URL link based on user input?

Question

I have a separate html page that does this with a php script, but I had help creating that php file which is just a form that allows users to enter a passcode that I provide them which will then simply link them to an external html page.  Since I don't know about php, I am thinking a possible work around would be to have a text input box which would allow a user to enter (passwordA) then click Submit to load (pageX.hmtl) or they could enter (passwordB) and Submit would load (pageY.html).  
If anyone knows how I could link my new flash project with my .php file, that would be great, or if there is AS3 code that would do this I would love that!

Answer 1

I have the php file on my server and the correct path in my as3 now.  Here are the exact codings I'm using:
AS3:
stop();
import flash.events.*;
import flash.net.URLLoader;
import flash.net.URLLoaderDataFormat;
import flash.net.URLRequest;
submit_btn.addEventListener(MouseEvent.CLICK, btnDown);
function btnDown(event:MouseEvent):void {
var variables:URLVariables = new URLVariables();
var varSend:URLRequest = new URLRequest("http://www.jmusicphoto.com/flashClient.php");
var varLoader:URLLoader = new URLLoader;
varSend.method = URLRequestMethod.POST;
varSend.data = variables;
passcode_txt.text = "";
submit_btn.addEventListener(MouseEvent.CLICK, passcodeSend);
function passcodeSend(event:MouseEvent):void{
variables.key = passcode_txt;
varLoader.load(varSend);
flashClient.php:
<?php
if($_REQUEST['key']) {
$key = $_REQUEST['key'];
$key = strtolower($key);
switch($key) {
case 'home':
header('Location: http://www.jmusicphoto.com/index.php');
break;
default:
echo "Oh noes!  You got something wrong.  You typed " . $key . " maybe there is a mistake?<br><br>";
break;
?>
Practically same php code is working here: http://www.jmusicphoto.com/EOSlogin.php   "home"