http://www.apnastuff.com/today-visitor.zip

Open Index.php and find:
require_once ROOT_DIR.'/engine/init.php';

Add after:

require_once ENGINE_DIR.'/modules/userstoday.php';

Find:

$tpl->set('{vote}', $tpl->result['vote']);

Add after:

$tpl->set('{userstoday}', $tpl->result['userstoday']);

Now add {userstoday} in your Templates/{Your-Theme}/Main.tpl to show this module.