For displaying posts from a custom post type you can use a wp_query()
object. In your case this is what you want :
<?php
$arg = array(
'post_type' => 'guide', // this can be an array : array('guide','guide1',...)
'posts_per_page' => 10,
'order' => 'DESC',
// 'category_name' => 6
'post_status' => 'publish'
);
$query = new WP_Query($arg);
if ( $query->have_posts() ) :
while ( $query->have_posts() ) : $query->the_post();
?>
<article>
<h2><a href="https://wordpress.stackexchange.com/questions/90978/<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php the_title(); ?></a></h2>
<div><?php the_excerpt(); ?></div>
</article>
<?php
endwhile;
endif;
wp_reset_query();
?>