Pockets are put on different ways. Can you tell me what you have done so far and what the directions tell you to do? I looked for the pattern, but only can come up with a picture of the back of the coat.
No pockets there!
Very often you'll bind off the stitches from the pocket opening, and on the next row, you'll replace those bound-off stitches with the live stitches from the pocket lining.
So you'd work up to the opening, work across the live stitches of the pocket liner, and then finish the row.
When the sweater is done, you'll sew the pocket to the inside.