Those abbreviations mean your cable is over 2 sts. Cb2 means you will put the first st on a holder, hold to the back, knit the 2nd st, then knit the 1st one off the holder. For cf2, you hold the first st to the front. For just one stitch you might not need a holder, though for your first few you might put it on something to see how it works. With a 2 st twist like this, I leave both sts on the left needle, knit the 2nd st first from the front, then the 1st st for the cb2. For the cf2, I knit the 2nd st first from the back of the work (not turning, just stick your needle between the 1st and 2nd sts), then knit the 1st one.