To bind off or cast off knitting, you secure the stitches in the last row worked so they don’t unravel. Binding off and casting off knitting is also called finishing the edge. Whatever you call it, it's easy to do.
Knit the first 2 stitches from the LH needle.
These become the first 2 stitches on your RH needle.
Unless otherwise told to do so, always bind off according to the stitch pattern given. If you would normally be working a purl row, purl the stitches when you bind off instead of knitting them.
With your LH needle in front of your RH needle, insert the LH needle into the first stitch worked on the RH needle.
This stitch is the one on the right.
Bring this loop over the second stitch and off the tip of the RH needle.
At this point, you have 1 stitch bound off and 1 stitch remaining on your RH needle.
Knit the next stitch on the LH needle so that you again have 2 stitches on your RH needle.
Repeat the preceding steps until you have 1 stitch remaining on your RH needle.
Cut the yarn a few inches from the needle and pull the tail through the last stitch to lock it.
If the piece you’ve just bound off is to be sewn to another piece, leave a tail that’s 12 inches long or longer for a built-in strand to sew up a seam.