Thumbnail Images | Post Excerpts | WordPress Theme Customizations

However, to display thumbnails manually, there will be an added step when you are posting your articles and there will be a line of extra codes to be inserted in your Index php file. First, open your Index php, look for these code:

<?php while (have_posts()) : the_post(); ?>

In between there will be other lines before you see this closing of the loop

<?php endwhile; ?>

Anywhere in between these 2 lines, insert this line:

via blogigs.com

Good trick for dressing up a home page in WP.