How to add custom css tyles to this tag page template

I have created a custom tag archive template.
it looks like this:

<?php /*
Template Name: Tag Archive
*/ ?>
<div>
<?php get_header(); ?>
<h2>Tag Archive</h2>
<?php wp_tag_cloud(''); ?>
	<div class="navigation">
<div class="alignleft"><?php next_posts_link('? Older Entries') ?></div>
<div class="alignright"><?php previous_posts_link('Newer Entries ?') ?></div>
	</div>
<?php if (have_posts()) : ?>
		<?php while (have_posts()) : the_post(); ?>
		<h2><a>" rel="bookmark" title="Permanent Link to <?php the_title(); ?>"><?php the_title(); ?></a></h2>
	<div class="entry">
	<?php the_content('Read the rest of this entry ?'); ?>
	</div>

	<?php endwhile; ?>
	<?php endif; ?>
</div>
<?php get_footer(); ?>

Can someone explain to me how to add custom css styles to this page. Mainly to make the tag links bigger, to align the title in the center, and make the tags alphabetical? Thanks