Help with comments php

I get quite a few comments on my blog and as a result many of my pages have large numbers of comments on the bottom.

It looks unsightly and I would like to be able to break them up with some graphical element, say every ten comments.

How would I write the PHP to do that? I am very new to PHP – all I have done so far is make simple edits to PHP code, never written anything new.

My current comment code is as follows (it is already configured to use a different css class for alternating comments):

<?php if ($comments) : ?>
	<h4 id="comments"><?php comments_number('No Responses', 'One Response', '% Responses' );?> to “<?php the_title(); ?>”</h4> 

	<ol class="commentlist">

	<?php foreach ($comments as $comment) : ?>

		<li class="<?php echo $oddcomment; ?>" id="comment-<?php comment_ID() ?>">
<div class="commentnumber"><?php echo $commentcount++;?></div>
			<cite><?php comment_author_link() ?> Says: </cite>
			<?php if ($comment->comment_approved == '0') : ?>
			<em>Your comment is awaiting moderation.</em>
			<?php endif; ?>
			<br />

<?php comment_text() ?>
<small class="commentmetadata"><a href="#comment-<?php comment_ID() ?>" title=""><?php comment_date('F jS, Y') ?> at <?php comment_time() ?></a> <?php edit_comment_link('e','',''); ?></small>

		</li>

	<?php /* Changes every other comment to a different class */
		if ('alt' == $oddcomment) $oddcomment = '';
		else $oddcomment = 'alt';
	?>

	<?php endforeach; /* end for each comment */ ?>

	</ol>

 <?php else : // this is displayed if there are no comments so far ?>

  <?php if ('open' == $post->comment_status) : ?>
		<!-- If comments are open, but there are no comments. -->

	 <?php else : // comments are closed ?>
		<!-- If comments are closed. -->
		<p class="nocomments">Comments are closed.</p>

	<?php endif; ?>
<?php endif; ?>

<?php if ('open' == $post->comment_status) : ?>

<h4 id="respond">Leave a Reply</h4>

<?php if ( get_option('comment_registration') && !$user_ID ) : ?>
<p>You must be <a href="<?php echo get_option('siteurl'); ?>/wp-login.php?redirect_to=<?php the_permalink(); ?>">logged in</a> to post a comment.</p>
<?php else : ?>

<form action="<?php echo get_option('siteurl'); ?>/wp-comments-post.php" method="post" id="commentform">

<?php if ( $user_ID ) : ?>

<p>Logged in as <a href="<?php echo get_option('siteurl'); ?>/wp-admin/profile.php"><?php echo $user_identity; ?></a>. <a href="<?php echo get_option('siteurl'); ?>/wp-login.php?action=logout" title="Log out of this account">Logout &raquo;</a></p>

<?php else : ?>

<p><input type="text" name="author" id="author" value="<?php echo $comment_author; ?>" size="22" tabindex="1" />
<label for="author"><small>Name <?php if ($req) echo "(required)"; ?></small></label></p>

<p><input type="text" name="email" id="email" value="<?php echo $comment_author_email; ?>" size="22" tabindex="2" />
<label for="email"><small>Mail (will not be published) <?php if ($req) echo "(required)"; ?></small></label></p>

<p><input type="text" name="url" id="url" value="<?php echo $comment_author_url; ?>" size="22" tabindex="3" />
<label for="url"><small>Website</small></label></p>

<?php endif; ?>

<!--<p><small><strong>XHTML:</strong> You can use these tags: <?php echo allowed_tags(); ?></small></p>-->

<p><textarea name="comment" id="comment" cols="100%" rows="10" tabindex="4"></textarea></p>

<p><input name="submit" type="submit" id="submit" tabindex="5" value="Submit Comment" />
<input type="hidden" name="comment_post_ID" value="<?php echo $id; ?>" />
</p>
<?php do_action('comment_form', $post->ID); ?>

</form>

<?php endif; // If registration required and not logged in ?>

<?php endif; // if you delete this the sky will fall on your head ?>