Remove custom form after submit

I have gotten the ajax submission down, now I need the form to fade out after submit with perhaps a message, "thank you for submitting".

<?php
/**
 * FORM API
 * Basic Contact form that inserts data into db and sends an email to both parties
 */

/*
 * Implements hook_menu()
 */
function contact_menu() {
	$items['contact'] = array(
		'title' => 'View the sample form',
		'page callback' => 'drupal_get_form',
		'page arguments' => array('contact_nameform'),
		'access callback' => TRUE,
		'type' => MENU_NORMAL_ITEM
	);
	return $items;
}
/*
 * Implements hook_theme
 */
function contact_theme() {
	return array(
	'contact_nameform' => array(
		'render element' => 'form',
		'template' => 'contact_nameform',
		),
	);
}

/*
 * Assign the elements of the form to variables
 */
function template_preprocess_contact_nameform(&$variables) {
	$variables['contact_nameform'] = array();
	$hidden = array();
	//Provides variables named after form keys
	foreach (element_children($variables['form']) as $key) {
		$type = $variables['form'][$key]['#type'];
		if ($type == 'hidden' || $type == 'token') {
			$hidden[] = drupal_render($variables['form'][$key]);
		}
		else {
			$variables['contact_nameform'][$key] = drupal_render($variables['form'][$key]);
		}
	}
	// Hidden form elements have no value to the theme
	$variables['contact_nameform']['hidden'] = implode($hidden);
	// Collect all form elements
	$variables['contact_nameform_form'] = implode($variables['contact_nameform']);
}


/*
 * Define the form fields
 */
function contact_nameform() {
// Assign form ID
	$form['#id'] = 'contact';
	$form['#contact'] = $contact;
	$form_state['contact'] = $contact;
// Fields
	$form['name'] = array(
		'#title' => t('Your Name'),
		'#type' => 'textfield',
		'#description' => t('Please enter your name.'),
		'#required' => TRUE
	);
	$form['email'] = array(
		'#title' => t('Your Email'),
		'#type' => 'textfield',
		'#description' => t('Please enter your email.'),
		'#required' => TRUE
	);
	$form['comments'] = array(
		'#title' => t('Comments'),
		'#type' => 'textarea',
		'#maxlength' => 500, 
		'#description' => t('Type you comment'),
	);

	$form['submit'] = array(
		'#type' => 'submit',
		'#ajax' => array(
		  'method' => 'replaceAll',
			'callback' => 'contact_nameform_ajax_callback',
			'wrapper' => 'box',
			'effect' => 'fade',
		'#value' => t('Submit'),
	),
);
	return $form;
}

/*
 * Form Builder; display confirmation of submission
 */
function contact_nameform_confirm($form, &$form_state) {

}
/*
 * Form submit function and email
 */
function contact_nameform_submit($form, &$form_state) {
	// POST Info
	$name = $form_state['values']['name'];
	$email = $form_state['values']['email'];
	$comments = $form_state['values']['comments'];
	
	$params['form'] = $form_state;
	
// New db_insert
db_insert('custom_contact')
		->fields(array(
			'name' => $name,
			'email' => $email,
			'comments' => $comments,
			'created' => REQUEST_TIME,
	))
->execute();

	// Send email to admin
	$admin ="doo@doo.com";
	$from = "foo@foo.com";
	
  $result = drupal_mail('contact', 'notify', $admin, language_default(), $params, $from, $send = TRUE);
}

/*
 * hook_mail().
 */
function contact_mail($key, &$message, $params) {
	switch ($key) {
		case 'notify':
			$message['subject'] = t('Asakos Website Contact Form - '. $params['form']['values']['name']);
			$message['body'][] = t('New information has been recorded. Contact information is below:')."\n".
			t('Name: '. $params['form']['values']['name']) ."\n".
			t('E-mail: '. $params['form']['values']['email']) ."\n".
			t('Comments: '. $params['form']['values']['comments']) ."\n".
			
			// Escape unintentional html inside of body
			$message['body'][] = check_plain($params['message']);
			break;
	}
}

function contact_nameform_ajax_callback($form, &$form_state) {
  $element = $form['box'];
  
  // if email get submitted succesfully
  $element['#markup'] = "Clicked submit with successful validation";
  
  // No it has not validated
  
  
  return $element;
}
?>

From my research so far, I need to add a form element like so:

	$form['confirm_message'] = array(
		'#type' => 'value',
		'#value' => $confirm,
		'#description' => t('Thank you for your interest!'),
	);

I then need to return the value of this element inside of the ajax callback.

Am I on the right track?

Thanks