Your PIN is a 4 digit number that you were asked to pick when you got your card. If you have forgotten your PIN & have an email address in your account then you can reset it by going to Log in/My OPL and after the boxes for Username or Barcode & PIN is a line that says Forgot Your PIN? When you click that link it will take you to a way to reset it.
If you don't have an email in your account you can stop by any of our branches, with a photo ID and staff can reset your PIN.