I am knitting a baby sweater (sacque) that started with 76 stitches for the back. I have worked the pattern for 7" as stated in the instructions. I don’t understand the next step for starting the sleeves. The pattern reads; discontinue pattern and work in stockinette st - this makes sense - then it continues; Sleeves - at begining of each of the next 2 rows cast on 42 stitches. Work on 160 stitches until sleeves measure 3 and 3/4" from underarm. Does this mean that I cast on 42 stitches, knit across, turn, then cast on another 42 stitches, and at this point knit in stockinette to the required sleeve length? And will I be able to see where the underarm should begin? The instructions then say to knit across 69 stitches and place them on a holder for the right front; knit 22 stitches and place them on a holder for the neck; knit remaining 69 stitches. The pattern then continues for the right and left front of the sweater. I understand how to put the stitches on the holders and where to go from there, I just don’t understand how to cast on the 42 stitches on each side. Any help would be greatly appreciated - thanks, Nancy:?? :wall: 
I just don’t understand how to cast on the 42 stitches on each side
Check this link. I use the e cast on when I have to do so at the end of a row.
There are other ways, one of them might be better.
For 42 sts, you need a sturdier edge than the backward loop provides, so use the knit or a loose cable CO. Then work across the new sts, and the ‘old’ sts to the end of the row. Turn and cast on again, working all stitches. The underarm begins with the cast on stitches, so work until 3 3/4" from the edge of the cast on sts, this will make the sweater look like a big T.
Thank you grumpy gramma and suzeeq. Both methods were simple to do. I ended up using the cable cast on and everything is back on track.:woohoo: