STEP-BY-STEP M1 MAKE 1 INCREASE
Insert the point of the right-hand needle under the loop or line of yarn that lies between the two stitches.
Next slip the yarn back on to the left-hand needle, ready for knitting.
Insert the point of the right-hand needle into the back of the stitch as if to knit.
Pull the yarn all the way through and you will now have an extra stitch on your right-hand needle.