When you are logged into manager.bidr.co, click on the items tab and find your raffle item:
Click where it says "399 tickets sold."
A new window will open that will show you all of your raffle purchases. You can use the search bar to find someone if you have too many tickets to scroll through.
This screen will display anyone who has won a ticket at the top. You can also refund raffle purchases here by clicking the "Refund" button.