To query for those contacts who have registered for past events, but have not yet registered for your current event, do the following:
 

  1. Go to Contacts > Individuals
  2. Click Advanced Search
  3. Expand Communities > Special Events > Friends Asking Friends
  4. Click Choose Event next to Kintera Thon
  5. Select all previous events
  6. Click Participants
  7. Click Add
  8. Set it for ALL participants
  9. Click OK
  10. Expand Communities > Special Events > Friends Asking Friends
  11. Click Choose Event next to Kintera Thon
  12. Select your current event name
  13. Click Participants
  14. Click Add
  15. Set it for ALL participants
  16. Click OK
  17. Click on this new "All Participants in Event(S)" on the right
  18. When that is highlighted, click the Not button at the bottom
  19. Run Query