It’s super-simple to do, but since it’s less-common, you might not be familiar with what to do.
Setup 1: Once you’re done crocheting a row, and before you turn or work any turning chains, just rotate your work 90 degrees clockwise.
Setup 2: Work a Ch3.
Setup 3: Skip the stem and work a DC in the same stitch.
Step 1: Skip the stem of the stitch.
Step 2: Ch1.
Step 3: DC in the next base.
Repeat steps 1 through 3 until you’re finished.
Practice makes perfect
Work a swatch of several rows of DC. On the last row, start working Setup 1.
Get comfortable with this and try it out now, before it’s on the official piece.