Pattern Help Please! I am so confused...

Hi all, I'm trying to make a wrap from redheart and I got everything down, except for this part.
The wrap is made in "sections" for slits and the direction says, "with right side facing and previous section in front of work, join yarn in 25th st on row 21..."

I get the joining part but what does it mean to hold previous section in front of work? I know the stitch overlaps the previous section by two so does that mean I work the stiches "behind" the previous section? How would I that?

Here is the pattern in case I am confusing you guys: