Arrived 1977 want to have duel citizenship what do I need to do?

I have gone though the Australia application and do not know how to go about it . I have rang twice citizenship.gov.au and still they have not returned my call . I turn 60 next year,have 3 adult children and one husband of 34 years . Please help as I would truely like to do this now rather than later. Cheers Carol Faye