The left and right sleeves are the same pattern.
(1)The next work begins to pick up yarn under the first stitch of the next needle (make one stitch)
(3)and it's to the right needle. 
Then you cover the stitch with the right stitch(It is a stitch that slipped on the right needle) Continue knitting to the middle of underarm. And,pm(A marker is in the middle of the underarm) 
Sew a hole with the yarn tail.
Distribute the stitches from your scrap yarn onto three double pointed needles. And join new yarn, Pick up stitches at underarm.
Pick up the stitch on the right side of the stitch on the left needle(make one stitch)
Then, k2tog the stitch and the first stitch on the left needle.
Knit to the point where you leave one stitch that was returned from the scrap
yarn to the needles.
Slide the last stitch to the right needle(slip 1sts knitwise)
(1)The next work begins to pick up yarn under the first stitch of the next needle (make one stitch)
