Measure the length of the window opening from the top edge to the bottom edge. Add 12 inches to the measurement so there is an adequate amount of fabric on the roller. Measure the width of the opening from one side to the opposite side. Write down all measurements on a piece of paper.
Spray the fabric with a liquid starch to stiffen it before cutting. Use the directions on the starch container to get a medium stiffness into the fabric. Lay the fabric on a flat surface to dry completely before continuing with the project. Press the fabric smooth with an iron after it dries.
Select a roller unit that fits the width of the window opening. Cut the starched fabric width to fit the width of the roller. Cut the fabric into the length determined in Step 1.
Fold the bottom edge of the fabric 1 inch to the wrong side and sew close to the raw edge to secure the hem. Fold the long sides of the fabric 1/4 inch to the wrong side and sew close to the raw edge to hem.
Measure 1 inch from the top edge of the fabric and draw a line across the top with an erasable marking pencil. Attach a piece of double-sided tape along the top edge of the fabric and stick the backside of the roller onto the tape. Use the marked line as a guide to keep the fabric straight on the roller.
Screw the roller brackets into the desired placement at the top of the window opening. Roll about 3 inches of fabric around the roller. Snap the roller into the brackets so the fabric falls to the front of the roller.