GT-511C3 Problem

i have leonardo and fingerprint GT-511C3. Library Fingerprint_Scanner-TTL-master. Pins 3 and 4 that is + and ground. Pins 1 and 2 that is RX and TX. How i can define serial in code? Leonardo has serial1 on pins 0 and 1, yes? Any combination in results display on serial text: "finger device not found".