At the most basic level, you want to do the following:

  • Add a new interaction on the timeline of a constituent who attended the event
  • Enter the Date as the date of the event
  • Subject should be something along the lines of attended the 2015 xyz Event
  • Purpose should be Special Event
  • Channel should be in Person
  • You might also have an interaction based custom field (Text/Pick One) for Event Name with values for each of your yearly events like Gala, Picnic, Fun Run, etc