Ok, this is one of those things that’s easy to sew and hard to describe with words. If it still hasn’t clicked by tomorrow, post again and I’ll try to knock up a photo or video clip.
If you take a peek at the illustration below that step, you’ll see there’s an arrow. It’s pointing up, toward the facing side (the side with the little lines, like sprinkles, used in the illustration to denote ‘facing’). See how there’s a stitching line (dashed line) that’s parallel to it? That’s where you’ll be stitching. And see the shorter stitching line perpendicular to it, in the middle of line you’re about to stitch? That’s the already-stitched together seam from step 4. And the straight (not dashed) line above that is the raw edge of the cut fabric, which is folded up, in the direction of the arrow, toward the facing side. When you stitch it this way, it will help ‘pull’ the whole works a tiny bit toward the inside of the dress, so the facing doesn’t show from the outside.
I HOPE that I both understood your question and answered it correctly but as noted, I haven’t made this dress in a long time and it is the middle of the night for me, so profuse apologies in advance if I’ve got it wrong!
