It is kind of hard to explain how to make cables without an extra needle. Let's say you have a two stitch cable. Transfer both stitches to your right hand needle knitwise. Take your left hand needle and insert it into the second stitch from the right on your right hand needle (either insert it in the front of the stitch or back of the stitch depending on which way the cable twists) leaving the first stitch alone on the needle. Gently pull both stitches off the right hand needle and quickly catch the loose stitch with your right hand needle and put it back on the left hand needle. (The other stitch will already be on the left hand needle.) Then knit the stitches which have already been twisted on the needles. Clear as mud? This is MUCH easier to do than explain.
What is that in the photo you ask? That is Trondheim, my much neglected Dale sweater. I am on the second sleeve and have to force myself to pick it up and work a few rows these days. It will go fast once I'm on the top yoke of the body of the sweater but until then it is deadly dull.