Insert the following code between the header and sidebar hook

main-content.php

	<div id="content">
		<h1 class="page-title"><?php the_title(); ?></h1>	
		<div class="entry-content">
                     <?php the_content(''); ?>
                                         <h3><?php _e('Looking for something? Try Searching...', 'aquamag'); ?></h3>
					 <?php get_search_form(); ?><br />
			<h3><?php _e('The Latest Articles', 'aquamag'); ?></h3>
			<ul>
				<?php query_posts( 'showpost=30' ); ?>
				<?php while ( have_posts() ) { the_post(); ?>
					<li><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a> - <?php the_time('Y.m.d'); ?> - <?php _e( 'Comments', 'aquamag' ); ?> (<?php echo $post->comment_count; ?>)</li>
				<?php } ?>            
			</ul><!-- Latest Posts -->
			<div class="clear"></div>
			
				<h3><?php _e('Archives based on Categories', 'aquamag'); ?></h3>
				<ul>
					<?php wp_list_categories('title_li=&show_count=true'); ?>
				</ul>
			</div><!-- Categories -->
			<!-- <div class="right" style="width:50%;">
				<h3><?php _e('Monthly Archives', 'aquamag'); ?></h3>
				<ul>
					<?php wp_get_archives('type=monthly&show_post_count=true'); ?>
				</ul>
			</div> --><!-- Monthly Archives -->
			<div class="clear"></div>
		</div><!-- .entry-content -->
	</div><!-- #content -->