This video will explain how to knit a left handed purl stitch.
We are beginning with a piece that has already been started. Every row has been knitted so far. Now on to the purl stitch. To purl, you will slide the left needle through the loop in front of the right needle. Keep the loose yarn in front of the needle. Use knit purl stitches together to create a "stockinette stitch" to knit left handed of purl stitch.