The easiest pillows to make are ones without zippers.
1. Start by measuring your pillow- The piece of fabric will need to be 2-3 times as long as it is wide. So, for a 30 inch wide bolt of fabric, you might buy around one yard, then split it down the middle of the width to make two 15x36 inch strips. This would be good to make two 14x14in pillowcases.
2. Next hem your edges on the shorts sides only.
3. With the right side of the fabric up, fold the long side so one end over laps the other. Sew the two open sides of the pillow together so the only opening is where you slip your pillow threw. Turn the pillowcase right side out.