HOW TO KNIT BACK AND FORTH ON CIRCULAR NEEDLES (FLAT KNITTING ON CIRCULAR NEEDLES)
1) Cast on all stitches the pattern calls for. As you cast your stitches, they will slide towards and onto the cable.
2) Work as if each tip of your circular needle were a straight needle. That is, hold one tip in each hand: hold the tip with the stitches in your left hand and the empty tip with your right hand.
3) Knit straight across all your stitches.
4) Turn all your work around by putting the tip in your right hand in your left hand, and viceversa.
5) Continue knitting your next row 
Or purling. Or whatever your pattern calls for…