Ok, im one step closer in finding the solution.
I believe the code should be:
<?php
$datetoday = date("d-m-Y");
$datepost = get_post_modified_time("d-m-Y");
if ($datetoday <= $datepost)
?>
*** here comes the html code that will be used for each post ***
<?php endif; ?>
But now i get an error for the line which contains <?php endif; ?>
What should it be instead?