The sleeves come in two pieces, top and bottom. Press button placket under upper sleeve and remove basting. Fold inside and press seam allowance at cuff. Check that length of sleeves is correct, then sew buttons on button placket. Sew them through all layers of fabric.
Buttonholes are optional.
Sew front seam of sleeves. Turn sleeves right side out and jacket wrong side out. Insert sleeves by sewing along easestiches Adjust ease by pulling on the stitching in the ease cap. Sew sleeve cap to jacket. There should be as much ease as possible, but no wrinkles at cap seams, when done.