Display full post of a specific category

I’ve looked through this entire forum and can’t figure this out. Let’s say I want to display the full post of category 24. How would I do that? Would I edit the archives.php, page.php (page template) or index.php?

Here is the page template code:

<?php
/**
 * The template for displaying all pages.
 */

get_header(); ?>
<div id="primary" class="site-content">
    <div id="content" role="main">
	<?php show_breadcrumbs();
        if ( have_posts() ) :
			while ( have_posts() ) :
			the_post(); ?>
			<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
				<div class="entry-content">
					<?php the_content(); ?>
					<?php wp_link_pages( array( 'before' => '<div class="page-links">' . __( 'Pages:', 'newsplus' ), 'after' => '</div>' ) ); ?>
				</div><!-- .entry-content -->
			</article><!-- #post -->
		<?php endwhile;
        else : ?>
			<article id="post-0" class="post no-results not-found">
			<header class="entry-header">
				<h1 class="entry-title"><?php _e( 'Nothing Found', 'newsplus' ); ?></h1>
			</header>
			<div class="entry-content">
				<p><?php _e( 'It seems we can&rsquo;t find what you&rsquo;re looking for. Perhaps searching can help.', 'newsplus' ); ?></p>
				<?php get_search_form(); ?>
			</div><!-- .entry-content -->
			</article><!-- #post-0 -->
        <?php endif; ?>
    </div><!-- #content -->
</div><!-- #primary -->
<?php get_sidebar(); ?>
<?php get_footer(); ?>

Please help. Thanks!