At the conclusion of your Meeting/Event, you can run a report of those who attended your Event.
From the Dashboard, click on the Reports tab
Select the Past Meetings button and the date range of the event.
Under Quick Sales Stats click on the 2nd square from the left (Participants) and choose Participant Details.
Next you will see the Meetings scheduled for the time range you specified.
To view the list of participants, click on the number of participants out to the right of the meeting name. To download the file into Excel, click on the gold download button to the right of where it says Meeting Attendees.