WordPress.org

1. Unzip into your /wp-content/plugins/ directory. If you're uploading it make sure to upload the top-level folder. Don't just upload all the php files and put them in /wp-content/plugins/.
2. Activate the plugin through the 'Plugins' menu in WordPress
3. Visit the Related Posts Options (in Settings Menu)

There are two ways to add the related posts to your content: 1. Use the admin to automatically add the plugin to your content. 2. Put this code into the WordPress loop:

<?php if (function_exists('sdac_related_content_by_type')) { sdac_related_content_by_type(); } ?>

Enjoy!