All the boring legal stuff....
NOIM (Notice of intended marriage)
A 'Notice of Intended Marriage' (known as a 'NOIM') is required to be completed by all marrying couples a minimum of one month out from your wedding, anytime up to 18 months out from your wedding. Page 3 of the NOIM is what you need to complete, then you should arrange to both meet up with a celebrant who must: sight your original forms of ID (a current or expired passport will suffice, otherwise a Birth Certificate and photo ID such as Drivers Licence); sight original proof of termination of any previous marriages (divorce or death certificates); and witness your signatures.
The NOIM is then retained safely by the celebrant until after your marriage when it is sent off to Births, Deaths and Marriages with the other paperwork.
Declaration of No Legal Impediment to Marry
Sometime within a few weeks prior to the wedding, your celebrant will need to meet with you to sign off on this document which declares that you are still free and clear to marry, and confirms your address and occupation (which will be reflected on the records at Births, Deaths and Marriages so needs to be current and correct). This form is sent off after the wedding to BDM along with the other legal paperwork.
Certificates of Marriage
During the wedding ceremony, there are 3 'Certificates of Marriage' for you both to sign, along with your two witnesses (aged 18 or over) and your celebrant. The celebrant sends one of those certificates off to Births, Deaths and Marriages after the ceremony, you get to keep the pretty decorative one, and the celebrant retains one for their records (usually in the big, red Marriage Register book)
Marriage Certificate (official certificate required for name changes)
Following the wedding, once Births, Deaths and Marriages has received all of the paperwork from your celebrant, they will register and record the details of your marriage and allocate a registration number. I can arrange the Marriage Certificate application form for you to sign to apply to receive this Marriage Certificate, showing the registration number recorded. Your signed application will then be sent off with all the other legal paperwork following the wedding - which saves you worrying about having to apply for it later! Their fee is currently $49.50 for a standard Marriage Certificate.