WordPress.org

Very simple, very easy:

1. Extract the zip file and upload both the hntitletotags.php file and the hnt2t directory to your web server a. In WordPress, upload to /plugins b. In WPMU, upload to the /mu-plugins for automatic site-wide activation. Obviously, skip step 2
2. Activate plugin by going to the Plugins section of your Control Panel
3. Configure the plugin by going to Options > Title 2 Tags in your Control Panel