Chalk marker from Michaels Metal chalkboards were purchased at Hobby Lobby for 40% off, regularly $4.99/ea. They currently sell these. Festive Star Accessory from Target Dollar Spot Magic Eraser from Kroger Ribbon from Hobby Lobby
Cut your ribbon about 20-25 inches long and then tie the ribbon to the chair back with a single loop. Pull as tight as you possibly can to secure it in place. It will likely slip a little and you’ll have to readjust every now and then, anyway.