I did the same type of walls several times. My best results have been by the following method: You will need: -1. A roll of painters black plastic -2. A box of grommets -3. A roll of clothes line. First unroll the Painters plastic as far as you can. Measure the height you will need all the way down the roll. Be sure it will just touch the ground, so as little ones wont trip on the slack, you can also trim once its hanging. You can either cut it or fold it over, making a double sheet. It should be about 3-6" above the ground, in the dark no one can see the floor anyway. My ceiling was in a warehouse so we did a 15' piece all the way around. Get a set of grommets from a hardware store. They are very easy to pop in and are cheap. Install one every 4' apart, near the top of your sheet. Be sure to put it about 6" from the top edge so it wont tear through. These give the plastic sheet the necessary strength while hanging, as it is VERY heavy once hung (otherwise the ropes will pull right through the plastic). Using a roll of clothes line, cut strips about 3-4' long (one for every grommet). Tie the strips through the grommet holes, then over a beam, or drop ceiling section, or whatever type of overhead you have. Making a loop right through the hole, then over the top is easiest. These strips also allow you to level the plastic if one side is off a bit. Over the years I have done about 13 different haunted houses. This has definately been the most succesful. It will save you money in the end since it easily reusable every year, by just untying it, and folding it away. Until i figured this method out, I was using new rolls of plastic and duct tape evry year, what a waste of money! If this is done corrctly, it should pretty much look like a BIG black shower curtain. Good luck