Posting and saving in Flash

Hey hi!
I got to create a web site for school. And I’m going to create a little flash, where someone posts sth very small and the last thing posted is shown in flash, and there is a form where you write and submit.
And it should save the stuff posted in a text and people should be able to look at it.
Actually, I have “no” idea where to start or what to do. Because I only know HTML, a little XML and AS. If someone could create something like that, it would be great because I could use it as a tutorial and learn some new stuff.
Thanks