Help Nested Comments in my Free Theme

¡Hi! I try, lot of times, but don’t understand php and the tutorials in spanish are very difficult to me.

¿Could someone help me to have nested comments in my theme? Here i have the code, please, tell me where i must do changes -i have nested comments in general options active yet- to make it possible. Thanks for your patience and for help me.

<?php // Do not delete these lines

	if (!empty($_SERVER['SCRIPT_FILENAME']) && 'comments.php' == basename($_SERVER['SCRIPT_FILENAME']))

		die ('Please do not load this page directly. Thanks!');

	if (!empty($post->post_password)) { // if there's a password

		if ($_COOKIE['wp-postpass_' . COOKIEHASH] != $post->post_password) {  // and it doesn't match the cookie

			?>

			<p class="nocomments">This post is password protected. Enter the password to view comments.</p>

			<?php

			return;

		}

	}

	/* This variable is for alternating comment background */

	$oddcomment = 'class="alt" ';

?>

<!-- You can start editing here. -->

<div id="comments"></div>

<?php if ($comments) : ?>

	<div class="comments-title"><?php comments_number('Sin comentarios', '1 comentario', '% comentarios' );?> para “<?php the_title(); ?>”<a href="<?php comments_popup_link();?>#respond">

	<span class="small">Deja una respuesta</span></a></div>

	<ol class="commentlist">

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

		<li <?php echo $oddcomment; ?>id="comment-<?php comment_ID() ?>">

			<?php echo get_avatar( $comment, 32 ); ?>

			<cite><?php comment_author_link() ?></cite> dijo:

			<?php if ($comment->comment_approved == '0') : ?>

			<em>//Tu comentario está pendiente de aprobación.//</em>

			<?php endif; ?>

			<br />

			<small class="commentmetadata"><a href="#comment-<?php comment_ID() ?>" title=""><?php comment_date('l, j \\d\e F \\d\e Y') ?> a las <?php comment_time() ?></a> <?php edit_comment_link('editar','&nbsp;&nbsp;',''); ?></small>

			<?php comment_text() ?>

		</li>

	<?php

		/* Changes every other comment to a different class */

		$oddcomment = ( empty( $oddcomment ) ) ? 'class="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) : ?>

<div class="respond-title"><h3 id="respond">Deja un Fantabuloso Comentario</h3></div>

<div id="comment-box">

<?php if ( get_option('comment_registration') && !$user_ID ) : ?>