Show a Wordpress Widget in the loop for the first post only

I need to display an ad banner just bottom of the first post in the loop. In order to administrate this banner the ad banner have to be widgetized. Here is the loop : <?php if (is_tag()) echo tag_description(); if (have_posts()) : while (have_posts()) : the_post(); // The following determines what the post format is and shows the correct file accordingly $format = get_post_format(); get_template_part( 'includes/post-formats/'.$format ); if ($format == '') get_template_part( 'includes/post-formats/standard' ); endwhile; else: ?> I don't provide FTP access, so you'll have to send the modified loop and the code that i have to add to my [login to view URL] wordpress file.