A little problem with Checkbox

I am new in all this…
I am creating a form with Flash and php; and I am using text, datechoose and checkbox.

This is the script I did:

stop();
var senderLoad:LoadVars = new LoadVars();
var receiveLoad:LoadVars = new LoadVars();

sender.onRelease = function() {
senderLoad.theName = theName.text;
senderLoad.theEmail = theEmail.text;
senderLoad.theMessage = theMessage.text;
senderLoad.inicio = inicio.text;
senderLoad.sendAndLoad(“http://www.mysite.com/send.php”, receiveLoad);
};

receiveLoad.onLoad = function() {
if (this.sentOk) {
_root.gotoAndStop(“success”);
} else {
_root.gotoAndStop(“failed”);
}
};

What I need to know is how do I create a var to see if a checkbox is click or not.

Here it is the php:

<?PHP

$to = "me@mysite.com";
$subject = “ADCO”;
$message = "Name: " . $theName;
$message .= "
Email: " .$theEmail;
$message .= "

Message: " .$theMessage;
$message .= "

Inicio: " .$inicio;
$headers = “From: $theEmail”;
$headers .= "
Reply-To: $theEmail";

$sentOk = mail($to,$subject,$message,$headers);

echo “sentOk=” . $sentOk

?>

Thanks for any help…
:mu: