How would I do this?

Hello, I’m pretty new to Blender and have a question. How would I do what the guy in this video is doing at 0:47:


If your talking about what he did by creating a new face that just scaled down, make sure you in face select mode and select a face, hit extrude (E) and dont move anywhere. Just hit S to scale it down and you’ll see how he does it. If you have any more trouble let me know

Thank you! I would have never figured that out by myself.