How to display featured posts like in the demo?

Hi, I like how this theme’s demo shows a mosaic of featured posts with their featured images, but I can’t find how to activate that display.

“Documentation” and other buttons at “About Blogbook” in WP Admin panel don’t work, they just take to the same page: …/wp-admin/themes.php?page=blogbook-welcome

Theme’s customize menus don’t show any option related to that.

If we can’t show that display this theme will be useless for our project.

So I hope you can help us.

Thanks in advance for any help …and take care!