This is a great tut if you need a visual concept of the process....love Jenny at MSQC......
the only thing I would add is to top stitch the little 'third' piece down perhaps an 1/8" from
the folded edge as it tends to not want to lay flat after washing and what mother wants to
have to iron a pillowcase when she is dealing with a sick child.....Jenny cuts her piece 2", I cut
mine 1-1/2" all depends on the look you want....