New blog template to display only one category

I understand that I can copy my theme’s default blog template and change the code to make it display only posts from one category in the theme’s style. I tried tinkering with it, but to no result yet. This is the code in the theme:

$posts = new WP_Query( array('post_type'=>'post', 'paged'=>$paged) );
            if( $posts->have_posts() ):
                echo '<div class="list-posts">';
                while( $posts->have_posts() ) : $posts->the_post();
                    get_template_part( 'content', get_post_format() ); 
                endwhile;
                echo '</div>';

                wp_reset_postdata();
            else:
                echo '<div class="alert alert-error">'.esc_html__('Sorry. There are no posts to display', 'gon').'</div>';
            endif;

I tried changing the values on while( $posts->have_posts() ) : $posts->the_post(); but to no success.

How can I make this work?

If your theme is creating a new query for the main page loop it is doing something very wrong. To get a category archive, all you should need is a template named according to one of these patterns, depending on your need:

1. category-{slug}.php – If the category’s slug is news, WordPress will look for category-news.php.
2. category-{id}.php – If the category’s ID is 6, WordPress will look for category-6.php.
3. category.php

With a Loop in it that looks like this:

if( have_posts() ) {
  echo '<div class="list-posts">';
  while( have_posts() ) {
    $posts->the_post();
    get_template_part( 'content', get_post_format() ); 
  }
  echo '</div>';
  wp_reset_postdata();
} else {
  echo '<div class="alert alert-error">'.esc_html__('Sorry. There are no posts to display', 'gon').'</div>';
}

Plus, of course, whatever code your theme needs surrounding that. I can’t really guess what that code looks like.