The purl stitch joins forces with the knit stitch to enable a knitter to conquer the world (the knitting world, at least)! You will often see the word purl abbreviated as p or P in knitting pattern shorthand.
Make sure your working yarn (the end attached to the ball of yarn) is in front of your knitting and insert the right-hand needle tip through the front of the first stitch from right to left.
Wrap the yarn around the right-hand needle tip from the top down. If you were to look straight at the tip of the needle, you would see that the yarn is wrapping counter-clockwise.
Pull the needle tip through the stitch on your left-hand needle, making sure to keep the yarn you just wrapped around the right-hand needle in place.
To complete the purl stitch, slide the worked stitch off of the left-hand needle. Your first purled stitch will now be wrapped around your right-hand needle.