Use the safety can opener top remove the top of the can and empty it out, saving the food in another container. Wash out the can and remove the bottom as well. Remove the label and use Goof Off to remove any residual glue or printing on the can.
Place the can down on a surface you aren't worried about scratching. Make sure the seam is down. Step on the bottom edge of the can to smash it closed, creating a pocket.
Turn the can over and use a hammer to smash the bottom edges of the can together. If you are using a large can the bottom edges probably won't close completely. That's just fine.
Cut two lengths of ribbon to 4 feet each. Loop the ends of each ribbon inside the can, on each side. Bring the ribbon back up and tie it to itself as shown in the photo. After you add the florals you can tie the long ends of the ribbons together so you can hang the arrangement.
Cut the floral block so that it fits inside the smashed can - it's easy to do this with a kitchen knife. Tuck the floral foam inside the can.
Add florals, securing them into the foam, to create a floral arrangement. Then tie the two ribbons together at the top in a bow so you can hang it on a hook.