Hi Tom,
The folder they used in the blog post is an example folder only. Your local folder may vary.
I've also provided a response to your other post with the same question. Using Toad for Oracle's built-in TNSNames Editor should help you do what you need to do. Here's the link to your other question.
http://www.toadworld.com/products/toad-for-oracle/f/10/p/34717/68723#68723
Feel free to let us know if there's anything else you need.
Thanks,
-John