I'm fairly new at knitting and I've decided to try to make a pair of mittens. However, I'm stumped on the thumb part of the Rowan Ash mitten pattern. It's a stockinette pattern and I've completed it up to the thumb. Can someone translate these directions for me, especially the parts in bold?
Cast on 20 sts and work in stockinette stitch (OK.)
K15 and turn. (OK, I understand this.)
Cast on and P 5 sts, P5 and turn. (So there should be five stitches left on my right needle?)
Work 6 rows on these 10 sts.
Break yarn and thread through rem 10 sts. Pull up tight and fasten off securely. Join thumb seam. (What thumb seam? Does this mean to sew the thumb together?)
With RS facing, rejoin yarn at base of thumb, K to end. 20 sts (huh?)