It will require some coding skills, but it is not hard. You first need to read this page in our documentation.

You can change the HTML, the style tags, delete stuff, add stuff in the copy of the results.php file.

I think this is the code you need (I am not sure though):

<?php echo wp_get_attachment_image( get_the_ID(), "thumb", "", "" );?>

This is from some code I wrote I while ago, here is a sub sample of the whole thing:

while ($query->have_posts()) {
  $query->the_post();
  $gallery_link_url = get_post_meta( attachment_url_to_postid(wp_get_attachment_image_url( get_the_ID(), "full", false )), $key = '_gallery_link_url', $single = true);
  if ($gallery_link_url == "") $gallery_link_url = "#";
  ?>
  <div>
    <h2><a href="<?php echo $gallery_link_url; ?>" target="_blank"><?php the_title(); ?></a></h2>
    <a href="<?php echo $gallery_link_url; ?>" target="_blank">
  <?php 
    echo '<span class="responsive">';
    echo wp_get_attachment_image( get_the_ID(), "thumb", "", "" );
    echo '</span>';
  ?>
  </a>
		</div>