You will use this technique when you knit a neck bank or a button band etc.
1. Right side facing you, hold you piece of beautiful knitting in your left hand. Insert the point of the needle through the first loop of the cast off stitch, wrap the yarn around the needle and pull the yarn through (just like a knit stitch)
2. Pick up the required number of stitches (usually one stitch for each cast on stitch, Now turn the knitting and continue in pattern.
I hope this helps and you find it useful.