display older post first in category page

hi, i would like to display my older post first in my category page. how to do it? following is my category page code

<h2 class=”page-title”><?php _e(‘Category Archives:’) ?> <span><?php echo single_cat_title(); ?></span></h2>

<div class=”archive-meta”><?php if ( !(”== category_description()) ) : echo apply_filters(‘archive_meta’, category_description()); endif; ?></div>

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

<div id=”post-<?php the_ID(); ?>” class=”<?php sandbox_post_class() ?>”>
<h3 class=”entry-title”>” rel=”bookmark” title=”<?php printf(__(‘Permalink to %s’), wp_specialchars(get_the_title(), 1)) ?>”><?php the_title(); ?></h3>
<div class=”entry-date entry-meta”><?php unset($previousday); printf(__(‘%1$s’), the_date(”, ”, ”, false), get_the_time()) ?></div>

<div class=”entry-content”>
<?php the_excerpt(”.__(‘read more »’).”); ?>
</div>

<div class=”entry-meta”>
<?php if ( $cats_meow = sandbox_cats_meow(‘, ‘) ) : /* Returns categories other than the one queried */ ?>
<span class=”cat-links”><?php printf(__(‘Also posted in %s – ‘), $cats_meow) ?></span>
<?php endif ?>
<span class=”comments-link”><?php comments_popup_link(__(‘0 Comments’), __(‘1 Comment’), __(‘% Comments’)) ?></span>
<?php edit_post_link(__(‘ – edit’), “\t\t\t\t\t<span class=\”edit-link\”>”, “</span>\n”); ?>
</div>
</div><!– .post –>

<?php endwhile; ?>