Here a description of the 3 parts:
1. The Server (or Account) widget (left widget).
2. The news header widget (upper right widget).
3. The reader widget (lower right widget).
The first thing to do is to set up an account now. This can be done by pressing the menu entry "Options->Accounts...". You must enter a name for the account and some specific data, and finally press "OK". Immediately afterwards this account should appear in the left widget. From now on this will be (one of) your News-Servers. You can specify as many accounts as you want. Ok, that's done.
The rest of the widgets will be filled automatically: clicking on an account and "Options->Newsgroups" will ask you for fetching the newsgroups for this account (=Server). If you have a connection to the Internet in this moment, say "Yes" and have a coffee. Fetching the groups may take some time, depending on the speed of your connection.
If you're ready, you should subscripe the groups of your interest in "Options->Newsgroups". After clicking "Ok", you should be able to open the account (in the left widget) by pressing the "+"-sign and see your groups.
Now you can click on one group, and kexpress will fetch all headers of this group (if you are still connected to the internet). And: your header and reader widget should be filled now.
That's all.