[Koha-devel] Not know how to use finesMode

Hello everybody. That's my first email so I hope I can express myself. I want to use the fines Mode but I'm not sure how to put it working. I have gone to "Circulation preferences" and I put the "finesMode" variable to "production", but it doesn't do nothing. I want to create a fine when anyone don't return a book on time, something like to pay $0,5 each day it overpass the "Specify Due Date". I suppose it must be done with "finesMode" but I don't know how to do it. What about "accruefines cronjob", where can I found it? I hope you can help me. Thanks!