I have a pvc hoop run with a tarp over the top. I used some plastic sheeting a painter left here to extend the covering over the run down to the ground on 2 sides. I untied the wires I used to attach the tarp and slid the top edge of the plastic under the tarp, then retied the wires going through the plastic. Then I used big head roofing type nails to tack down the bottom edge to the bottom of the 2x4 frame. After that I used hay strings tied together to go over the plastic from the front of the run to the back and tied them to the wire. Actually, without a picture of your set up, it is hard to say what would be the best way to attach the plastic. You can do a lot of things with duct tape, bungee cords, hay string, etc, etc, but need to know what your set up consists of to be able to advise. We had some fairly strong winds last night and all my plastic is still in place...yaay!