Help with "backlog"

[Danielle Lajoie]

 I'm new to Trello. I listened to a video that  had set up (4) different columns with. Within each column were "backlogs" and tasks. The idea was  to slide the backlog into a specific task. I really think it's a great way to get organized. Does anyone know how to do this? Are there any Power-ups that would facilitate this? I'm attaching a PIC -I'm referring to the first column on the left.

Thanks

Danielle