The roller skate buttons had reasonably large loops on the back, so it was easy to pass the folded hairband through the loop. The other buttons had smaller loops, so I had to find some little bands, and it was more fiddly to get the band through.
Once the band was through, I looped one end through the other and tightened the band. I also added a spot of hot glue to the bands on the back of the each button so that the band was held in place.
A was very pleased with her new hair bands, and immediately wanted one in her hair.