It starts full of comments, that show the current settings of most things. To change any setting, uncomment that line and edit it. The options are documented in man knews , and only apply to that news server. This command reads your settings into the X options database. You can have one file per X11 application, or one shared file.
News is held on the Internet by several news servers.
Local special interest groups may setup their news servers to retain articles for months. You have to remain on-line to read them. You can setup your own news server, which acts as an automatically driven news reader, to fetch all texts to your local machine. You then point knews at the local server. This means that you can read news off-line, and that you can have private news groups.