Renaming the field label from "author" to "created by"
To rename the label of a field add the preprocess function template_preprocess_node to your template.php file:

function *YOUR THEME*_preprocess_node(&amp;$vars){
  //Supposing that your content type name is "group"
  if($vars['type'] == 'group'){
    //Supposing that your field name is "field_txt_group"
    $vars['content']['field_txt_author']['#title'] = 'created by';
  }
}