Adding form label to search module?

Hello,

I need to add a label to the text input field in the search module. Can someone please show me how to do this. I'm quiet new to editing Drupal.

I think this is the php that creates the search form?:

/**
 * Output a search form for the search block and the theme's search box.
 */
function search_box($form_id) {
  // Use search_keys instead of keys to avoid ID conflicts with the search block.
  $form[$form_id .'_keys'] = array(
    '#type' => 'textfield',
    '#size' => 15,
    '#default_value' => '',
    '#attributes' => array('title' => t('Search the HeliJobs site')),
  );
  $form['submit'] = array('#type' => 'submit', '#value' => t('Search Jobs'));
  // Always go to the search page since the search form is not guaranteed to be
  // on every page.
  $form['#action'] = url('search/node');
  $form['#base'] = 'search_box_form';

  return $form;
}

and the label details:

<label for="edit-search-theme-form-keys">Search Jobs:</label>

I'm very grateful for any help!