Posts in 3 columns

Hi everyone, I’d like to know if there’s a way to display posts in 3 columns. So the featured image, and right under it the post content.

Basically:

picture | picture | picture
1 2 3

I’ve been trying to do this with just css but it isn’t working out for me.

Here’s what I have so far:

<div id="main-wrapper">

<?php
  $loop = new WP_Query(array('post_type' => 'camp', 'posts_per_page' => 3));
  if ($loop->have_posts()) ?>
    <?php while ( $loop->have_posts() ) : $loop->the_post(); ?>
    <?php
    $custom = get_post_custom($post->ID);
    $screenshot_url = $custom["screenshot_url"][0];
    $website_url = $custom["website_url"][0];
?>

    <div id="camp-boxes">
<?php the_post_thumbnail( 'campcol'); ?>
 <?php the_content(); ?>
    </div>

<?php endwhile; ?>

</div>

Any ideas?