Leaving a 10 inch tail at the end of the yarn, place a slipknot on one of your needles.

Take the yarn from the skein and wrap it around your thumb, securing the end in your hand with your other fingers. 

Insert the needle up under the front of the yarn and gently tighten the loop on the needle.

Continue until all stitches have been cast on.

Video Demonstration: Backwards Loop Cast On