StudioPress Community Forums - How to modify the "single page loop?"

I want to use a related posts plugin with the Corporate Theme, and have the location and styling of the related posts links up to me. I figured on doing this by adding code similar to the following into the theme's single.php file

Code:

if ( function_exists('related_posts') && is_single() )  { 

?>        

<div class="postpost">

        <h4>Related Posts:</h4>

        <?php related_posts(); ?>



        Get new Keener Living posts via RSS or Email or on your Kindle.

        





        <h4>Bookmark and Share:</h4>

        Tweet This

        Stumble This

</div>

<?php }

The problem is that I cannot find a single.php file. I looked for a theloop file to see if it took place of the single file and did not see it either. Basically I cannot find where in the code I need to add the above to get it to show for single blog posts.