Help me please:) don't understand pattern

This is from the Debbie Bliss Baby Knits Patterns “Dress with eyelets” Has anyone else made this??

This is the “back opening” section and it says:

K14(17:20:23) sts, turn and work on these sts for first side of back opening
next row cast on 3 sts, k these 3 sts, then p to end
next row k to end
next row k3, p to end

So I understand that “turn” means that I flip it around like I’m at the end of a row when I’m really in the middle of it (total work is 49 sts long at this point and it has me K23 then turn), and I figured out how to cast on in the middle of a row, but now when it says “next row k to end” do I knit all the way across the entire 49 plus the 3 new that I just cast on in the middle? Or when it tells me “work on these sts for the first side of back opening” does that mean I totally ignore the other half now? I don’t see where I would finish the other half though…

Thanks!

Only work the stitches on this side. If you work all the stitches, you’ll reconnect the back rather than keeping the two sides separate.

When this side is done, I’m sure they’ll tell you to put the other stitches on the needles to finish the second side.