I am a beginner, and glad I found this site. I am knitting a cardigan and have the stitches for the sleeves on a piece of yarn. I finished the body, bound off and cut the yarn ball off. Now I have to go pick up the stitches of the sleeves and put them back on the needle. How do I reattach the yarn ball to these stitches? I've already moved them onto the needle and off the stitch holder, but don't know how to start knitting again since the yarn ball is unattached. Thanks!