Trim the frayed or torn ends of the webbing.
Coat the ends with waterproof glue to prevent them from unraveling further. Allow the glue to dry completely.
Thread the upholstery needle with the waxed dental floss. Using about 18 inches of floss, pull 9 inches through the eye of the needle, then tie the ends of the floss together in a firm knot. Tie another knot on top of that one, so you have a large, thick knot at the end of the floss.
Sew the ends of the nylon webbing together with even chain stitches about a 1/2 inch long and no more than an 1/8 inch apart. If you are adding a new piece of nylon to bridge two short pieces that have been damaged, sew each end of the new piece to each damaged piece about a 1/2 inch beyond the glued ends. If the webbing is thick, you may need to use pliers to push and pull the needle through the webbing.
When the two ends are securely sewn together, or you need to re-thread the needle to continue, push the needle through to the back of the webbing and run it under the last two stitches, tying it off in a knot around the second-to-last stitch.