Flash and XML

Hello everyone,
In fact this is my first participation in this great forum. I was looking for some
help when by chance ( a golden one) came across this helpful forum.
Anyhow, I need your help.
My problem is this.
I want to use an xml file as a database and use flash to extract the data concerned. My fla includes an input text and dymanic text fields for different nodes of elements to be shown and a submit button. In other words, the user will enter an ID number so the flash extracts the data and shows it in the relevant Dynamic text boxes. I need your help in writing a simple code for the submit button in flash and the relevant data in the xml file so I can enlarge it or add the number of users I wish.

Let’s say I have a class and each student wants to see her/his marks.

I’m sure I’ll find here who can give me a hand.
Thanks in advance.