The sleeves are knit as part of the back, that's why you cast on 16 sts. So you'll have the back pattern, then work the first row of the sleeve pattern and CO 16 sts. Then work the next row across all the sts and CO 16 sts for the other sleeve. Same for the front, then you likely seam the shoulders and the front and back of the sleeves at the top and underarm. That should work out right, though it may not look like it until you get several rows of the pattern worked. And it could be that the first few rows of the sleeve pattern are not in pattern so they can be seamed at the lower edges.
sue- knitting heretic