calling item for use in grid

Hello,

I am trying to make this featured image the main item in a visual studios grid. Or, the item that appears in the lightbox when you click on it. I don’t know if this is enough code to get some help, but any guidance on how I could call this item here would be massively helpful. Thanks!

$thumb = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), ‘full’ );

echo ‘<div class=”work-item ‘. $postclass .'”>’;
echo ‘<div class=”work-img-2″>’;
echo ‘‘;
echo ”. the_post_thumbnail( ‘full’, array( ‘class’ => ” ) ) .”;
echo ‘<div class=”work-overlay”>’;
echo ‘<div class=”work-description”>’;
echo ”. the_title( ‘<h3>’, ‘</h3>’ ) .”;
echo ‘<span>’. $tax .'</span>’;
echo ‘</div>’;
echo ‘</div>’;
echo ‘‘;
echo ‘</div>’;
echo ‘</div>’;