If the apk is launched in a device with no NFC then it will exit instantly.
If the device's NFC is not enabled when the application is launched then it will directly open the settings and show a toast dialogue saying "Please enable NFC and press Back to return to the application!"
Press select file, a complete action dialog will appear.
Select a way of how you'd like to select your file. Then select your file.
File name will appear on the top side of the screen.
Enable NFC on your destination device.
Set the devices back to back.
Tap to beam the selected file to the destination device, wait until the file is transferred.