When you start Informant, the first window you see will be the Manager. From there, click on the "Newsgroups" button.
In the "Newsgroups" window, you can subscribe to or unsubscribe from any newsgroups. Click on the "Refresh" button to download a list of all newsgroups from your server. Once you have a list of newsgroups, select any one that you want to subscribe to, and click on the "Subscribe" button. You can double-click on any subscribed group to bring it up in a separate window.
In the Newsgroup window, you can manage the headers and bodies for a particular group. Click on "Refresh" to download headers, or select a message listing, and click on "Get Body" to download that message's body. If the body is already downloaded, simply select it, and the body will be displayed. To reply to any message, click on the "Followup" button.
When composing a message, simply type in whatever you want to say, then click on the "Send" button to post the message.