prova con questo codice HTML

codice:
<html> 
<head><title>TEST iFRAME</title></head> 

<body> 
<table border="1" width="500" height="400"> 
  <tr>
    <td height="50">HEADER</td>
   </tr> 
   <tr>
     <td height="300">
       <iframe src="testo.html"></iframe>
     </td>
   </tr> 
   <tr>
     <td height="50">FOOTER</td>
   </tr> 
 </table> 
</body> 
</html>