Hello @marin,

This section can be set up by choosing the post, page, category and custom text.

So if you chose post, category then you can go to individual post edit screen and add the preferred content in text editor and that will be displayed. Similarly, as for page go to individual page edit screen.

As for the custom type you can directly add the text from the customizer.

Screenshot:
http://prntscr.com/k9q1a9

Hope this helps.

Thank you.

Best Regards!!