Take 2 selected cloth napkins and iron out wrinkles.
Pin trim right side to right of one napkin with edge of trim to edge of napkin.
Stitch the trim to the edge of the napkin about 1/4" allowance. I tried to sew as closely to the edge of the napkin as the trim would allow and not show so that I retained as much of the size of my 20" square napkins to cover my 20" square pillows.
Lay the second napkin with the right sides together and stitch three sides. On the bottom, stitch in to the center about 3" on both sides and back stitch, leaving an opening to insert pillow form.
Turn pillow cover right side out.
Measure your opening and cut that amount of sew on velcro, the hook side on the inside edge on one edge and the loop side on the other side of the opening.
Roll pillow and insert into the opening. Push the corners of the pillows into each corner of the cover. Close and move pillow until it has taken the shape of the cover.