Guestbook code

I just have added the guestbook template!
but here is the problem.
I’d like to add some sentences before the “Leave a Comment”, but I can’t. this is the page–> my guestbook
this is my guestbook code:
———————————————
<?php
/*
Template Name: guestbook
*/
?>
<?php get_header(); ?>
<!-- content ................................. -->

<div id="content">

<?php if (have_posts()) : ?>
<?php while (have_posts()) : the_post(); ?>

<div class="feedback">
<?php comments_popup_link('Add comment', '1 comment', '% comments', 'commentlink', ''); ?>
</div>
<?php comments_template(); // Get wp-comments.php template ?>

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

</div>
<!-- /content -->

<?php get_footer(); ?>
——————————————-

Does anyone know what to add in this template?
Thank you! ??