How to show only 4 latest posts?

put this code above your loop
$featured_posts = array(‘post_type’=>’your post type name’,’posts_per_page’=>4);

I have this kind of code:

<?php while($featured_posts->have_posts()): $featured_posts->the_post(); ?>
<div id="htmlcaption_<?php echo $post->ID; ?>" class="slider-text nivo-html-caption">

<span class="date"><?php the_time('F d, Y'); ?></span>

<div class="slider-heading">

<h2><a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php the_title(); ?></a></h2>
<p><?php echo string_limit_words(get_the_excerpt(), 40); ?></p>

					</div>

Where should I put the code?
And what is my post type name?

sorry for my noobness

you can set posts per page from your dashboard also
from settings->reading->posts per page