What you need:
1 yard of cotton or voile fabric (I prewash mine when making pillowcases)
thread and other sewing notions
1. Line up your selvages, square the right side of your fabric, and trim to 30 inches long.
3. Sew along each raw edge with a 3/8" seam allowance. (See above picture.)
4. Turn pillowcase inside out (so now the right sides are together) and poke out corners. Press seams.
5. Sew along each side again, encasing raw edges, with a 1/2" seam allowance.