It's quite simple actually.
Two pieces of fabric cut to the size you want the pillow (with an extra 1/2" to 1" for a seam allowance). You can also just fold a piece of fabric and half and it leaves you with only three sides to sew : ) Easier is always better, so that's what I did.
Place the two pieces of fabric together (right sides against each other). Sew the pillow all the way around, leaving a hole large enough for your hand to fit through. I back stitch when I start and stop so the seam won't unravel. That's simply starting sewing for an inch, sew backwards on top of that back that same inch, then start sewing forward again right on top of those two. You end it the same way.
Then turn your pillow right side out. Stuff it with filler. Then whip-stitch the fabric closed by hand. I just start the thread inside the pillow, then sew back and forth until I get to the end. I double up the thread when I first thread my needle, so when I'm done I just cut it off the needle and have two threads to knot at the end.
It really is just that simple! For me, this was a free outdoor pillow project (my favorite kind). I had the fabric and stuffing. As I've mentioned before. I keep all pillow stuffing out of pillows I am getting rid of for future projects. I also keep any fabric I can (from bedding, clothes, friends etc.) to use. This fabric came from a picnic blanket that was wrapped around some outdoor cushions I bought a few years ago from Target.
Another free project intended to inspire : )