How do I make these pleats?

I am very interested in the pleats that are on this sweater:

However, I am having trouble understanding the suggestions her co-worker made for making the pleats in an easier fashion:
"‘I know how you could have done those pleats without seaming!’ and suggested knitting a few rows, folding it down, then securing the pleat by knitting the top directly into the purl bumps of the corresponding row. If I were to do it all over again, that is what I’d do."

How do you knit “the top into the purl bumps”? Thanks in advance to those who respond with helpful suggestions. Any other advice about other ways to make pleats would also be appreciated.

Also, her pleats look a little bit thick. Do you know how I would make mine appear less bulky?

I think what she’s saying is that as you knit the edge and get the pleat, when folded, the length you want, you’ll knit the next row together with the purl bumps on the back.

I’d put my right point through the top of a purl bump on the back and left it onto the left tip and knit them together.