Working back and forth?

How-to Questions
1

The pattern reads: "From this point, the upper front will be worked back and forth in rows. The two remaining markers indicate side seam placement.

UPPER FRONT
BO 3[4, 4, 5, 5, 5] sts at beginning of next 2 rows. 96[111, 128, 143, 161, 175] sts.
P 1 row"

https://knitty.com/ISSUEsummer07/PATTcoachella.html

What should i do? (im mostly confused about the BOs and how to do them having the stitch holder in the middle)

2

Ignore the sts on the holder (The 10sts for size small). Work back and forth (knit flat) on the remaining sts. Knit to the gap created by the held sts, turn and purl back.
For the smallest size that’s 23sts, marker, 56sts, marker, 23sts.