//On the client side, you create your request
jQuery(document).ready(function(){

  $("a#myclicktrigger").click(function(){  //Click event
    //Will post the data to mypage.php when the link #myclicktrigger is clicked
    $.post(
      "/ajaxtest", 
      {action:"showmessage"},
      function(data){ $("a#myclicktrigger").after('<p class="txt">'+data+'</p>');}
    );   
    return false;
  });
  
});