Create a Facebook Campaign that is promoting the event, its time, place, have a registration form that people can fill out (so I can get their name, email etc). The same form will act like a entry into winning free tickets.
To increase their odds at winning the contest, we can include our refer-a-friend feature that will give someone extra points towards winning if they get their friends to enter the contest too.
You can use [login to view URL] or any other [login to view URL] program if needed.