Featured Slider – can't figure out how to link images to pages

I installed this theme here
I can get a link to show up on the main image, that is associated with that image, but it then associates that image with all the rest of the images… Any idea how to fix it?

Here is a link to the current code: Click Here

This is the code I was trying to replace the current image with:

<?php if($custom_link !== "") {
					 echo '<a href="'.$custom_link.'">';
						 $attr = array('class' => "", 'title' => $custom_caption);
						the_post_thumbnail('image_xxl',$attr);
					 echo '</a>';
					} else { ?>
                    <?php
						$attr = array('class' => "", 'title' => $custom_caption);
						the_post_thumbnail('image_xxl',$attr);
					?>
					<?php } ?>