Purchase blue screen fabric from a reputable photography and/or lighting supply store. How much fabric you get may depend on your production needs, but a minimum of 3 yards is recommended. If you don't want to buy blue screen fabric or you want to save money, get a light blue bedding sheet that matches the color of blue screen fabric.
Place the blue screen fabric on a flat surface. With a ruler and pen, mark points for grommets to go in each side of the fabric. Allow enough space between grommets so that when the fabric is stretched it will be tight and flat. Wrinkles may cause problems when filming. Once the points are marked, use a grommet tool to punch in grommets.
Find PVC tubing that matches the height of the stand you wish to make, at least 5 feet. You may have to find or purchase several pieces of PVC tubing along with enough ells or slips (corner pieces). Put the tubing together so that it forms the "frame" of your blue screen backdrop.
Guide the rope through each grommet point in the blue screen fabric for each side of the frame. Allow enough slack so that you can tie off the rope on each pole. When all sides of the fabric are done, tie off each side using a strong knot.
Stand your new blue screen stand flat against a wall. If you wish, you can construct a base on each side of the frame so that your blue screen backdrop becomes portable.