Some documentation is provided with the Leafnode package (read the files INSTALL and README, the sources are also quite interesting). If you want to know more about "professional" and "big" news servers, check the INN FAQ (they are provided with the INN package). To get information about your newsreader, type man "name of your newsreader" or check for other files in /usr/doc.
If you have any questions concerning the news system, just ask in an appropriate newsgroup (look in the news.software.ALL hierarchy).
If you have any question, comments or corrections concerning this HOWTO, just write to me (email@example.com).