Drupal add library

// Add as a library
  drupal_add_library('project18', 'project18_block', TRUE);
...
/**
 * Implements hook_library().
 */
function project18_library() {
  $libraries['project18_block'] = array(
    'title' => 'Project 18 Block library',
    'js' => array(
      drupal_get_path('module', 'project18') . '/js/ajax_refresh.js'
    ),
    'css' => array(
      drupal_get_path('module', 'project18') . '/css/style.css' => array(
        'type' => 'file'
      ),
    )
  );
}