Form Submit to lightbox

Hi Group.

I have an html page where a form submits to a php page. It works, but the php page loads an entire page to return just one variable. I was thinking there would be a better and neater way to return the php in the form of a lightbox or modal.

Here is my form code

<form method="post" action="doadd.php">
<textarea name="message" cols="20" rows="18"></textarea>
<input type="submit" value="Create" />
</form>

Code (markup):

my doadd.php has the following.

$message = $_POST['message'];

Code (markup):

It inserts this data into a database and then echos the results to the doadd.php page for the user to see.

The results are just a single line, hence the need for a simpler box.

Any help appreciated!