Untitled

header.tpl:
<html>
 <head>
  <title>..</title>
  ..css, scripts, etc..
 </head>
 <body>
  <div id='header'>
   ...
  </div>

forum-topic.tpl:
{include file='header.tpl'}
  {foreach from=$posts item=post}
   <div class='post'>
    {$post->text}
   </div>
  {/foreach}
{include file='footer.tpl'}

footer.tpl:
 </body>
</html>

viewtopic.php:
// $posts already contains the posts from MySQL
$smarty->assign('posts', $posts);