In step 3 when creating a challenge you have to choose between Hero or Superhero:
HERO: When closing your challenge, you can mark how many percent you have achieved. The donations will be divided according to your result. If you agreed to quit smoking for a year, but you have failed after 6 months, you still achieved 50% of your challenge. As such 50% of the fundings will go to charity organisation and 50% will return to the sponsors (as credits on the website).
SUPERHERO: For Superhero's the "all or nothing"principle applies. If you have met the challenge, 100% of the funding will go to the charity organisation. If you have not met the challenge, the entire amount will return to the sponsors (as credits on the website)