When you end a piece of knitting you must secure all the stitches you have finished by "casting off". This should be done on a knit row but you can employ the same technique on a purl row: the stitches, whether knit or purl, should be made loosely. When casting off rib, you must use both knit and purl.

In A Knit Row

Casting Off in a knit row Casting off in a knit row b

1. Knit the first two stitches and insert the tip of your left hand needle through the first stitch

2. Lift the first stitch over the second stitch & discard it. Knit the next stitch & continue to lift the first stitch over the second stitch to the end of the row. Be careful not to knit too tightly. For the last stitch, cut your yarn, slip the end through the stitch and pull the yarn tight to fasten off securely

In A Purl Row

Casting off in a purl row

Purl the first two (and all subsequent stitches) & continue as for knit stitch above.