I just finished a bag that requires twisted cord for the handle, so I thought I'd explain (the best I can) how to make it.
Start with yarn cut to 4 times the length you need. Example, if you want a 15" cord (before knotting) cut yarn 60" long.
How many strands of yarn you use depends on how thick or thin you want the cord. This will also depend on the type of yarn you use. Remember that the yarn will be folded in half, twisted and folded in half again. Six strands of Bernat Softee Chunky will make a cord about 3/4 in diameter.
I use a D clip to attach the yarn to a door knob (so you won't need a second person). Hang the D clip on the knob, put yarn through and fold in half. Just start twisting tightly.
Your cord should look like the picture to the right when all twisted.
Fold cord in half again (remember not to let go of the loose ends or you will have to start all over again). It will look like a tangled mess, but if you run it through your hand while pulling down on it, it will straighten out.
Now remove it from the door (still do not let go of loose ends) and remove it from the D clip. Knot both ends. Cut the doubled over ends for fringe.