You now have your RSS stream which appears in your favourites. If you ad others, you will see these appear automatically. It is up to you to create your own categories depending on how you want to sort your entries.
If you double click on one of them, a tab containing all the different streams will appear on the right.

Next, if you click on one of the entries, information about it will appear below.

But if you double click on it, the internal RSSOwl browser will open so that you can consult the news page yourself.

It is now up to you to add the streams that you want and to look around the software a little so as to discover all its secrets! You can change your preferences / Tools, and if you look around you will notice that you can change quite a lot of settings.
This program is based on tab navigation, which means you can easily have 10 streams open at the same time, switching between them with the corresponding tab (like with Firefox). If you double click on a tab, it will close. The streams list will automatically refresh itself depending on the time since its release.