I need my pages to display post previews

Hello, I am new to wordpress and I am trying to build my first site. I would each of my pages to display a certain category of posts.
I have created a page template and inserted a query before the loop but this however loads the entire post onto the page. I would just like to load the preview like on my homepage.
https://www.adveteurs.com

Also, I would like to add text before the posts. Do I simply type what I would like on the page in WordPress.

Here is the code for the duena theme

get_header(); ?>

	<div id="primary" class="col-md-8 <?php echo esc_attr( of_get_option('blog_sidebar_pos') ) ?>">
		<div id="content" class="site-content" role="main">
				<?php while ( have_posts() ) : the_post();{
						query_posts( 'cat=GAP' );
							}
							?>
					<div class="page_wrap">
						<h1 class="entry-title"><?php the_title(); ?></h1>
						<?php the_content(); ?>
					</div>
					<?php
						// If comments are open or we have at least one comment, load up the comment template
						if ( comments_open() || '0' != get_comments_number() )
							comments_template();
					?>

				<?php endwhile; // end of the loop. ?>
		</div><!-- #content -->
	</div><!-- #primary -->