A simple CI tutorial question

Hi there!
I'm totally new to CI and know little about html/php,when I read CI user guide,
a section of code in tutorial/news section confused me:

Code:

<h2><?php echo $title; ?></h2>
<?php foreach ($news as $news_item): ?>
        <h3><?php echo $news_item['title']; ?></h3>
        <div class="main">
                <?php echo $news_item['text']; ?>
        </div>
        <p><a href="<?php echo site_url('news/'.$news_item['slug']); ?>">View article</a></p>[code]

<?php endforeach; ?>
[/code]

Where does the 'class="main"' come from? Where can I edit it?
Anyone who answers will be a great help to me.
Thanks!!