How to work into cast-on stitches

Hello, everyone. This is my first post. I am making a beautiful baby afgan called “Knit Fan Stitch Shawl”. It is featured in a VERY old Coats and Clarks Baby Book #251 (The price on it says $0.50!). The fan border pattern of 79 rows goes all the way around a center garter stitch rectangle of 100 stitchesX200 rows, with the border worked separately for each side. After completing the 79 row pattern on the first side of the rectangle, the instructions call for you to bind off. Then the instructions read “Working along opposite side of cast-on sts, pick up and k 110 sts. Repeat rows 2-79. Bind off as before.” I do not know how to “pick up” from cast-on stitches, and I’m not sure which is the “opposite side of cast-on sts”. Can someone help me?

On what side did you work the first edging? Usually, the side opposite the cast-on edge would be the end of your knitting–I assume in this case the end of the rectangle.

Picking up stitches is the easy part.

That’s worded kind of strangely, but I think the stitches would get picked up on the cast on stitches, wouldn’t they, so you can work in the other direction? I’m picturing that you knit the starting rectangle, then continue on for 79 pattern rows and bind off. Then go back to the cast on row and pick up along that edge, so you can work from the bottom down. Then pick up along each side to complete the border.