Flex Builder 4 - Send and Receive Data from PHP File

Hope someone can help me. Although I have some background in programming, I am quite new to web development. I am trying to to connect a flex builder 4 to a PHP file. I created a form and httpservice which sends two fields to php via "GET". Everything seems ok apart the fact that I am having difficulties in creating a responde from the PHP and read it back to flex application. I know that I have to use httservice lastResult in order to g开发者_StackOverflow中文版et data back from PHP. Could anyone show me a step by step simple code that output something xml in PHP that lastResult will get and display it as mx.Alert.show() for example ?

A simple google search produced this tutorial:

http://www.flashrealtime.com/flash-builder-4-and-php-data-services/