I just used the same instructions as my monogrammed pillow for the base and just added grosgrain ribbon instead of the monogram. It's an envelope pillow cover, so you can sew it in around 15 min!
You could use an old pillow, or just a plain one you want to spice up. Just make sure you can take the pillow cover off the pillow. I added the trim before I sewed the front and back together.
This is what I did. I used 5/8" white grosgrain ribbon and 5/8" heat and bond. First Iron your heat & bond onto your ribbon.
Now cut out a 8.5" x 8.5" square and a 2.5"x 2.5" square out of paper. ( This is for a 18" x 18" Pillow) This is going to be your template for the ribbon. I then grabbed a piece of chalk, yes you heard me right kinda of weird but I promise it works wonders. It's white and you can see it easily on the dark fabric, it also blends in with the white ribbon. I measured on all sides of the square to make sure it was perfectly even, then trace around your template.
Grab your small square and line it up with the corner of your big square. Measure on all sides to make sure it's even, then outline it with chalk.
Now you have your template ready to go. Grab your ribbon that already has the heat & bond attached and start placing it on. I placed the ribbon down the middle of the line, but i'm not a perfectionist. You could place it on the outer edge to get a more acurate placement. Then start ironing as you go.
When you come to a corner, this is what you do. Go forward just a little bit then pull it back towards you.
Then fold it down at a 45 degree angle, until it looks like this. It looks more complicated then it really is and once you get the hang of it it's really easy.
Now when you come to the end just tuck it in at a 45 degree angle and iron down. Now just sew on the back of the pillow cover and your done. Yeah!!! give yourself a pat on the back!!!