how to get posts from specific category but …. pls help me

use the ‘category__and’ parameter in the query;

where exactly do you need help?

read:
https://codex.www.ads-software.com/Template_Tags/get_posts
https://codex.www.ads-software.com/Function_Reference/query_posts
https://codex.www.ads-software.com/The_Loop
https://codex.www.ads-software.com/Class_Reference/WP_Query
https://codex.www.ads-software.com/Class_Reference/WP_Query#Parameters
https://codex.www.ads-software.com/Class_Reference/WP_Query#Category_Parameters
https://codex.www.ads-software.com/Function_Reference/get_cat_ID

i use this code to display latest from a specific cat

<ul>
		<?php $recent = new WP_Query("cat=34&showposts=5"); while($recent->have_posts()) : $recent->the_post();?>
		<li><a href="<?php the_permalink(); ?>"><img src="<?php echo bloginfo('template_url'); ?>/lib/scripts/thumb.php?src=/<?php
		$values = get_post_custom_values("thesis_thumb");if (empty($values)) {echo '/wp-content/themes/thesis_18/custom/noimg.png';}; echo $values[0]; ?>" alt="<?php the_title(); ?>" class="footer-thumb" width="35" height="35" /></a>
		<div class="recent-post-content-featured">
		<p><a title="Post: <?php the_title(); ?>" href="<?php the_permalink(); ?>"><?php the_title(); ?></a></p>
		</div>
		</li>
		<?php endwhile; ?>
		</ul>

how can i do to show latest from a specific category but to be in the “featured” cat too ?

try to replace this line:
<?php $recent = new WP_Query("cat=34&showposts=5");
with:

<?php $featured_id = get_cat_ID('featured');
$recent = new WP_Query( array('category__and => array(34, $featured_id), posts_per_page' => 5) );