<script>
		$(function(){
			$('input[type=submit]').click(function(){
				$.ajax({
					type: "POST",
					url: "test.php",
					data: $("#myform").serialize(),
					beforeSend: function(){
						$('#result').html("<img src='loading.gif' />")
					}
					success: function(data){
						$('#result').html(data);
					}
				});
			});
		})
	</script>

<form action="start.php" method="post">
	//Code
	//ein submit button
	<?php
		if(bedingung){
			//Hier soll dann mein Knopf eingeblendet werden
			echo '<form action="" method="post" onsubmit="return: false;" id="myform"> <input type="submit" text="load" name="load" value="Load more!"><div id="result"></div></form>';
		}
	?>
</form>