You have the choice of either letting votes determine the winner or selecting a winner yourself based on your own criteria defined in your rules. This option is chosen under the "Timeline & Voting" tab when you create your contest. Once your promotion has ended, you can download your data by logging into your account. For contests, you can select your favorite entry, or if you've opted to have votes choose the winner, you can sort by the number of votes and find which entrant has the greatest number. Once you've selected a winner, verify that they meet your criteria and contact them directly.