It's probably also quite buggy. There is no other way to set configuration options. Also, the only way to subscribe newsgroups is to hand-edit the newsrc file, which is in standard UNIX newsrc format. There is basically no multi-threading. You can only have one newsgroup open at a time.
Source code is included.
The javac program handles dependencies automatically, so there's no Makefile. Just 'javac NjnAWT.java', and the application should build properly. The code shouldn't be too hard to follow, and is even mostly commented.