1. Go to the Flickr website and log in to your account
  2. Go to the Apps By You page in the App Garden
  3. Click Get another key
  4. Choose Apply for a non-commercial key
  5. Enter a name and a description and check the two waiver checkboxes before submitting
  6. Copy the Key and the Secret to the fields above, and click Save settings
  7. Now you can go to the Import tab, and you'll be prompted to log in to Flickr from Piwigo