<script type='text/javascript'>
 function form_send(){
   f=document.getElementById('the_form');
   if(f){
     f.submit();
     }
   }
 </script>

<form method='post' action='your_post_url.html' id='the_form'>
  <input type='hidden' value='whatever'>
</form>

<span id='subm' onclick='form_send()'>Submit</span>