To 'rejoin' yarn, you just begin knitting with it at the place indicated, leaving a tail long enough to weave in later. The cable cast on is on the Cast ons page. But insert your needle at the point you're to begin the cast on and wrap the yarn around it - that's the first stitch instead of a slip knot. Then knit into the st but leave it on the needle and put the new stitch on the Left needle too. Then for cable CO, insert your Right needle in between the 2 new sts and wrap the yarn then put the new st on the L needle. Do that until you've got 12 new sts.
sue- knitting heretic