PHP, Flash, and Client usability

Ok, I’m not asking for a tutorial (though one would be great) or for a ton of answers, just a general way of how things work and what tools are needed to get this specific task done.

I have a flash file with a dynamic text field. The text comes from my file homeSchedule.php and works wonderfully with my movie. My question is, how do I build a backend to a site so the client can login, go to “Edit Schedule”, send the information to the database via the backend, and have the PHP file read it.

This is rather lengthy and I understand that I sort of answered my own question. I understand how mySQL works and how PHP works to an extent, just need a lot more clarification or a step in the right direction.

Thanks again!