1. there should be some small rubber bands on the umbrella (assuming you bought them in a packet, if you didn't, tie the fins back with thin twine or string in step 6), take them off but do not discard
2. open out the umbrella
3. carefully tear out all of the supporting struts of the umbrella so as not to tear it or break the spokes
4. remove the sliding hub the struts were attached to
5. put umbrella inside-out and bunch up (still inside out)
6. replace larger of the two rubber bands removed earlier in a way that will hold the dart closed.