Casting Off
Casting Off or Binding off, is the process of removing all stitches from your knitting needle so that they don't unwind.
1) Knit 2 stitches onto your left hand needle.
2) Using the right hand needle, lift the back stitch (the first one on the left needle) over the top of the top stitch and off the needle. This puts a knot on that stitch and removes it.
3) Knit another stitch onto the left needle and repeat step 2 untill all but the last stitch is left.
4) Cut the yarn. Thread the yarn end through the last stitch to secure it. You can thread the yarn end and sew through a few stitches to ensure it is completely secure.