A few years ago, I bought one of those "purple paisley shirt" type garments. It was a shiny, dark, silver shirt that I'm sure no one else had a use. I bought it to make a gift bag. I used most of the back to make the bag and kept the rest, because I just can't throw away a piece of fabric. This Christmas I've been making clothes for 2 little girls' 18" dolls. When I came across this shirt, I discovered the 2 sleeves.
In what is now the back of the dress, tack the ribbon so it won't slip out. I used a decorative stitch. You could just tack if you like.
Create a narrow hem on what used to be the top of the sleeve. I used a decorative stitch on each dress.