Welcome back to the Wisteria KAL! I hope your swatching efforts went well and you are ready to get started on this sweater! As I've mentioned before, this pullover is worked in pieces and it starts with the back. Start the back by casting on the indicated number of stitches, then work in 2x2 ribbing (K2, P2) for 3 inches. Next, continue in stockinette stitch (knit on the right side, purl on the wrong side) for 14 inches, or until your desired length to the underarms. Make a note of the length you decide to work because it will be important when it comes time for the front. Time to shape the armholes!
Armholes are generally shaped with a large decrease worked by binding off stitches on each side, then working decreases for a number of rows for shaping. Depending on the size you are making, you will bind off 5 or 6 stitches at the beginning of each row; this is because you can only bind off at the beginning or in the middle of a row, but not at the end of a row. To follow this instruction, begin your row by knitting 2 stitches, then pass the first stitch on the right-hand needle over the second and off the needle. This is the same way you would normally bind off when finishing a project, but only do this process 5 (6) times. After binding off the indicated number of stitches, knit across the rest of the row. Repeat this process at the beginning of the next row as well. For more information about how to work a bind off, click here. The result is that you have 10 (12) fewer stitches and a notch at each side of your sweater for the underarms.
Following the bind off rows are a series of decrease rows. The decreases, as described in the pattern, are worked one stitch in from edge, making seaming easier because the edge stitch is worked normally. Two different kinds of decreases are used because each of these decreases has a slant or lean to it; using them on their appropriate sides creates nicely shaped armholes. A k2tog (knit 2 together - right slanting) is used for the left side and an ssk (slip, slip, knit - left slanting) is used on the right side of the sweater. You can see more about how to work these decreases here. Once you have worked the decrease row on the knit side, follow it with a purl row and repeat the indicated number of times for your size.
Once these decreases are finished, you're home free! Just "work even" until you have reached the indicated length, creating the depth of the armhole. "Work even" means go back to working in stockinette stitch with no decreasing, as you did for most of the back. Done! Bind that piece off and admire your work - one piece down!
Once you have completed the back, feel free to start on the front; it starts the same as the back, but the neck shaping starts 2.5 inches before the armholes. If you are working as written, this means the neck shaping will start at about 11.5 inches, but if you worked the back for 16 inches for example, you would work the front to 13.5 inches. We'll pick up there next week by continuing the front with both neck and armhole shaping!