Add a css style or class

can someone help me add a class to this?
echo $curuser->display_name;
its working fine but i can’t change the styles of it!

here’s my full loop if that helps:

<?php
/**
 * The template for displaying Author Archive pages.
 */

get_header(); ?>
<div id="main">
            <div class="main-section">
				<div class="headline">
                    <div class="holder">
                        <h1>Blog</h1>
                    </div>
                </div>
                <div class="main-content">

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

				<?php $author_id=$post->post_author; ?>
			<?php endwhile; ?>
			<?php
$args=array(
   'showposts' => 15,
   'author' => $author_id,
   'caller_get_posts'=>1
);
$posts=get_posts($args);
if ($posts) {
  $curuser = get_userdata($author_id);
  $author_post_url=get_author_posts_url($curuser->ID, $curuser->nicename);
  echo "<h2>$curuser->display_name;</h2>"
  foreach($posts as $post) {
    setup_postdata($post); ?>
    <h3 class="category"><?php the_category();?> </h3>
					<div class="blogContainer">
						<div class="blogpiece">
						<div class="titleMeta"><div class="metaDeets">by <?php the_author_posts_link(); ?> | <?php the_time('g:i') ?> | <?php the_time('d/m/Y') ?></div><h6><?php the_title(); ?></h6></div>
						<div class="mainText">
							<?php the_excerpt(); ?>
						</div>
						<div class="readMorebox"><a href="<?php echo get_permalink(); ?>">&raquo; Read more</a></div>
					</div>
				</div>
    <?php
  } // foreach($posts
} // if ($posts
?>
</div>
</div></div>
<?php get_footer();?>

Thanks ??