You will find the solutions to the competition questions on the Big Challenge website in summer 2020.
You can view your personal result, i.e. your score and your ranking, by clicking on this link using the personal code you received at the end of the competition. If you no longer have that code, the coordinating teacher at your school can give it to you (they can see it in their user account). The prizes will be sent to your school and are also distributed by your teacher.