How make Sub headings for this code, help

<header id="topMenuHeader">
     <div id="topMenuHeaderInner" class="wrapper">
     <ul class="menu">
     <li class="first"><a href="signature-pools.php" title="Signature Pools">Signature Pools</a></li>
   
  <li><a href="vandrro.php" title="Vandrro">Vandrro</a></li>  
  <li><a href="dynamic-architectural-fittings.php" title="Dynamic Architectural Fittings">Dynamic Architectural Fittings</a></li>
  <li><a href="toughstore.php" title="Toughstore">Toughstore</a></li>
           
  <li><a href="captrad.php" title="Captrad">Captrad</a></li>
  <li><a href="general-grp-mouldings.php" title="General GRP Moldings">General GRP Moldings</a></li>
  <li><a href="s-plas.php" title="S-Plas">S - Plas</a></li>
  <li class="last"><a href="composite-timber.php" title="Composite Timber">Composite Timber</a></li>
  </ul>
  </div>
  </header>