the celebrant will organise the intent to marry form for you and file it too.
there is a celebrant website that is like a registry - has a whole bunch of celebrants from all over the country, lists what services they offer, whenre they are prepared to travel, etc. Something like 'celebrant-e" dot com.
If you do go the registry route, you will need to do it yourself. you can print the form from online, and you need to submit it (in vic) one month and one day before the intended ceremony. You will need full original birth certificates (not extracts or photocopies) and ID to lodge the form.