Can't add a header and background to a column

So here is a link to my blog: https://oxoxtali.com

What I’m trying to do is add background, header, and footer images to my blog column (the left one).

I’m working in a child theme. Here is the coding I’ve got to try and accomplish this in my style.css file:

#content {
    margin-top: 60px;
    width: 580px;
    padding: 20px;
}

.posts_top {
    background-image: url('https://i1096.photobucket.com/albums/g335/oxoxtali/backgroundforblogcolumn_zpsa0462ad1.png');
}

.posts_middle {
    background-image: url('https://i1096.photobucket.com/albums/g335/oxoxtali/bgfinal_zps79803259.png');
}

.posts_end {
    background-image: url('https://i1096.photobucket.com/albums/g335/oxoxtali/bottomcolumn_zps6191770b.png');
}

Then I’ve got this coding on my .php pages:

<?php get_header(); ?>

<div id="insidewrapper">

<?php get_sidebar(); ?>

	<div id="content">

        <div id="posts_top"></div>

        <div id="posts_middle">

	<?php if (have_posts()) : ?>

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

	<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>

<!-- title side section -->

		<div id="metarea">

		<h2><a href="<?php the_permalink() ?>" rel="bookmark" title="Link to <?php the_title_attribute(); ?>"><?php if(the_title( '', '', false ) !='') the_title_attribute(); else echo 'Untitled';?></a></h2>

			<div class="bypostauthor postauth">By <?php the_author_posts_link(); ?>
			</div>

			<div class="date"><?php the_time('F jS, Y') ?>
			</div> 

		</div>

		<div id="contentholder">

		<?php the_post_thumbnail(); ?>

			<div class="entry">

			<?php the_content('Continue reading &raquo;'); ?>

			</div>

				<div class="pagelink"><?php wp_link_pages( 'before=<p class="link-pages">Page: ' ); ?>
				</div>

			<p class="info"><?php comments_popup_link('No comments yet', '1 comment', '% comments', 'comments-link', '<div class="commentoff">no comments</div>'); ?> </p>

			</div>

		</div>

		<?php comments_template(); ?>

		<?php endwhile; ?>

		<div class="navigation"><?php if(function_exists('wp_paginate')) {} ?>

		<?php next_posts_link('&laquo; Previous Entries') ?>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<?php previous_posts_link('Next Entries &raquo;') ?>

		</div>

		<?php else : ?>

		<h2>Not Found</h2>

		<p>Sorry, but you are looking for something that isn't here.</p>

		<?php endif; ?>

		</div>
	</div>

        </div>

        <div id="posts_end"></div>
</div>

<?php get_footer(); ?>

</div>

<?php wp_footer(); ?>

</body>

</html>