WordPress.org

You can install this plugin in the standard way from the WordPress plugin admin screen, or you can download its files and upload the php-snippets folder to the /wp-content/plugins/ directory.

1. Upload the php-snippets directory to the /wp-content/plugins/ directory
2. Activate the plugin through the 'Plugins' menu in WordPress
3. Create a new post or page
4. Notice the new <?php button in the TinyMCE toolbar -- click it to get a list of available PHP Snippets, then select the one you want to insert it into your post.
5. Optionally, configure your custom snippet directory under the Settings --> PHP Snippets directory and put in the /full/path/to/your/directory