Post box background not expanding :( ?

Hi Guys!
This is already my third time to post this concern of mine. Up until now, no one has ever helped me o give an advice with regards to my concern. I’m really getting frustrated. I know how to how to repeat a 1px background image in css

#postbox-center {
position:absolute;
left:212px;
top:466px;
width:601px;
height:1px;
background:url(images/postbox-center.jpg);
background-repeat:repeat-y;

but I don’t know where to insert the div tag “postbox-center” in the index.php. Is it around the container div?…,entry div?…,around the <?php the_content(); ?>, or I’m just going to replace the container div with the postbox-center div? Please guys help me out..or show me an example(“,).

<div id=”container”>
<?php if(have_posts()) : ?>

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

<h2>“title=”<?php the_title(); ?>”><?php the_title(); ?></h2>

<div class=”post” id=”post-<?php the_ID(); ?>”>

<div class=”entry”>

<?php the_content(); ?>

<p class=”postmetadata”>
<?php _e(‘Filed under:’); ?> <?php the_category(‘, ‘) ?> <?php _e(‘by’); ?> <?php the_author(); ?>
<?php comments_popup_link(‘No Comments »’, ‘1 Comment »’, ‘% Comments »’); ?> <?php edit_post_link(‘Edit’, ‘ | ‘, ”); ?>
</p>

</div> <!– entry div end –>

</div> <!– post div end –>

<?php endwhile; ?>

<div class=”navigation”>
<?php posts_nav_link(); ?>
</div>
<?php else : ?>

<div class=”post” id=”post-<?php the_ID(); ?>”>
<h2><?php _e(‘Not Found’); ?></h2>
</div>

<?php endif; ?>

</div> <!– container div end –>