Does anyone have any knowledge about how to copyright?
I know the copyright office is in Washington, DC but cannot get anyone on the line.
I want to know if a GROUP of short stories/poetry could be copywritten as a GROUP (one Number) and not individually?
Thank You.

Yes, they can. Anything you write and that is complete or "fixed" is immediately copyrighted. Put on each finished piece or group of pieces, e.g., c2016, Wondergirl.

Here's more about that from a reliable, legal site:

Copyright is Automatic | Nolo.com

Agreed, there is no need to contact anybody at the copyright office. I've always used the form "(c) [Year] [Your name, or company name] All rights reserved."