Yahoo does not supply newsgroups.  Not Usenet anyway.

You can view and use Google Groups which are (mostly) a Usenet feed.

Yahoo Groups are private list servers with a message (web) access
option.  After you "join" a gropu it sends messages by e-mail.  You
can reply by e-mail or use the web interface.

Google Groups cannot be accessed either by Outlook. Only web browser.  
Google has also started offering private list servers the same as
Yahoo and erroneously lists them under their "groups" option.  
Google's groups are not Usenet.

Both Yahoo and Google seem to muddy the waters by the way they use
terms and mix content

Newsgroups with names such as
"microsoft.public.windows.inetexplorer.ie6_outlookexpress" are a part
of what is known as "Usenet" news groups, and was the first exchange
area for topical posts on the Internet.  It preceeded things such as
list servers, message boards, etc.

Now everyone seems to have their own flavor of this which confuses
people endlessly.

DMK

Check your clock & or Time Zone? Bye.