Help with Login Using Flash MX, PHP, and MySQL

i followed this tutorial and it kicks ***.
the only problem is that it doesnt have a register users section.
becuase of this i have decided to take it upon myself to create it.
the only problem is that i am not that experienced at PHP and MySQL.
i have created the user registration form in flash. this has multiple information fields:
-first name
-postcode (i live in the UK)

all input fields have the same variable name, without spaces of course.

what i want to happen is when a user submits the form an email is sent to them informing them of their login details (username and password) an email sent to the site admin (me) informing me of their registration and also the variables inserted into a database table.

i read a tutorial that sends the variables from the form into an email (its on the kirupa flash tut’s) so i thought i would incorporate this into my new php file.

this is the code so far:

$sendTo = . $_POST["email"]; 
$subject = "Welcome to the LS12Style Website!";

$headers = "From: Ashley Broadley"; 
$headers .= "<[email protected]>
$headers .= "Reply-To: [email protected]
$headers .= "Return-Path: " . $_POST["email"]; 
$message = echo "Dear " . $_POST["firstname"] . " " . $_POST["surname"] . " <br>Thank you for registering with the LS12Style website. Your login details for the website as follows:<br>Username: " . $_POST["username"] . "<br> Password: " . $_POST["password"] ;
mail($sendTo, $subject, $message, $headers); 

i want the message to be what i want it to say but including some variables from the form.

any help with this?

thanks in advanced