[SOLVED] Tiny Tiny RSS does not work as expected

I installed TinyTiny RSS without problem, but it does not work as expected.
I added two feeds:

But the feed are are not shown. I see in the left column that they are added.
In the main window I read:
Feeds zuletzt aktualisiert am Thu, Jan 01 1970 - 2:00

I have found no way to add catogories.

You can add categories from the Actions -> Preferences -> Feeds page.

Now I know, how I can add categories. Thank you.
But ther is still no content of the feeds shown.

I solved it myself. I had to choose “ungelesen” to see the feeds.

So my question can be marked as solved.

Since this issue has been solved, I am marking it as [SOLVED] in the title.