Here's the beginning of the pattern -
Cast on 132 sts. Do not join. Working back
and forth across needle in rows, proceed
1st row: (RS). K26. (P2. K24) 3 times. P2.
2nd row: K2. (P24. K2) 5 times.
Rep last 2 rows 3 times more.
You'll be purling the stitches in between on the front and knitting them in the back. Once you finish this section you'll start cabling. It'll make sense once you start working on it. Just follow the pattern. Using markers might be helpful.