You can’t. Google Groups does not carry the “binary” Usenet newsgroups. Google Groups only makes available a subset of the text newsgroups.
Note: “binary” means “files” in Usenet lingo.
Daily Usenet traffic is over 7.5 terabytes. That’s more traffic than all of google.com. So, providing a free Usenet server, with all of the binary groups, is not something that is easy for even the largest companies.
And so, if your ISP does not provide a Usenet server as part of your internet access, you will have to sign-up with a third-party service such as Easynews.
Note: Google Groups does not offer NNTP access either. So, you can’t use standard NNTP news-reader software to access the service, or email programs like Thunderbird.