adding multi-column text in sections

First, GeneratePress is really cool!!!

I have a question in doing with sections. I'm trying to add a section with multi-column texts shown from the video. I think I followed the way in the video to add sections. But I cannot get multi columns which shows some text content?

One solution said that I could install Lightweight Grid Columns, but I don't think the video installed that plugin since there is no add column button in the text editor of the video.

Can you help me out?

Thanks!!