Purl one into front of stitch, then back of stitch...How?

I would like to know how to Pfb on the wrong side…I’m working on the Danica scarf from the latest Knitty and I’m already stuck on the Pfb…Thanks , Liz

The first stitch you purl as normal, but don’t slide it off. On the second sticth, insert your needle into the back loop, from left to right, wrap, purl and then slide off the needle.