PHP - Export Content to MS Word document

<form name="proposal_form" action="<?php echo htmlspecialchars(stripslashes(trim($_SERVER['PHP_SELF']))); ?>" method="post">
  <input type="submit" name="submit_docs" value="Export as MS Word" class="input-button" />
</form>
<?php
  if(isset($_POST['submit_docs'])){
          header("Content-Type: application/vnd.msword");
          header("Expires: 0");//no-cache
          header("Cache-Control: must-revalidate, post-check=0, pre-check=0");//no-cache
          header("content-disposition: attachment;filename=sampleword.doc");
  }
  echo "<html>";
  echo " <h1>PHP - Export Content to MS Word document</h1>
        <p>This is a test.<p>";
  echo "</html>";
?>