Knit two stitches together to give a right-leaning decrease.
1 Insert the point of the right-hand needle through the loops of the next 2 stitches as if to knit.
2 Wind the yarn round the tip of the right-hand needle and pull the yarn through the 2 stitches, knitting them both together.
3 Drop the 2 stitches from the left-hand needle and keep the new stitch on the right-hand needle.
4 Knitting two stitches together decreases your stitch count by one, and the decrease stitch leans to the right. This is how a series looks.