Drupal creating a template for an existing form

<?php
/**
 * Implements hook_theme().  
 */
function mymodule_theme($existing, $type, $theme, $path) {
 
  return array(
    'mymodule_print_mail_form' => array(
      'render element' => 'form',
      'template' => 'mymodule-print-mail-form',
    ),
  );
}
 
/**
 * Implements hook_form_FORM_ID_alter().
 */
function mymodule_form_print_mail_form_alter(&$form, &$form_state, $form_id) {
  $form['#theme'] = 'mymodule_print_mail_form';
}
 
?>

<h1>My Custom Print Mail Form is soooo RAD.</h1>
<?php
// render the name and address fields out of order
print render($form['fld_from_name']);
print render($form['fld_from_addr']);
// print the rest of the fields - this has to be here for the form to work.
print drupal_render_children($form);
?>