Search your inbox for "PledgeBox".

If that doesn't work:
1) Click - https://survey.pledgebox.com/user/register
2) Signup and login as a backer with the email address you used on Kickstarter/Indiegogo
3) All the projects you have backed will be shown.
4) Click on the ‘View’ button to edit your information.
5) Complete the survey and then you can see all the details.