WordPress.org

1. Upload results-count.php to the /wp-content/plugins/ directory
2. Activate the plugin through the 'Plugins' menu in WordPress
3. Place <?php wp_searchheader()?> in your templates, where you want the text generated by the Results Count plugin to occur.

If you want to ensure that the plugin is installed first to stop errors with the template when it is disabled, then instead use the code:

<?php if (function_exists('wp_searchheader')) : ?>
<?php wp_searchheader()?>
<?php endif; ?>

Which will then automatically check for the plugin before trying to execute it.