how to translate a link

Create a post how to translate?

I know what's in the code, but how to do it right I do not know ... in this form t ('')

/**
 * Implements hook_commons_bw_create_all_widget().
 */
function commons_posts_commons_bw_create_all_widget($group) {
  if (og_user_access('node', $group->nid, 'create post content')) {
    $link = l('Create a post','node/add/post',
    array('attributes' => array('class' => 'commons-posts-create'), 'query' => array('og_group_ref' => $group->nid))
    );
    return array(
      'commons_posts' => array(
        'default' => TRUE,
        'link' => $link,
        'text' =>  t('Foster a topic through commenting'),
        '#weight' => -1,
      ),
    );
  }
}