OK you are so not alone in this. You can probably emigrate to a range of countries without having to complete as much paperwork as you do for this .... First you need to claim for the Child Care Benefit - even if you are not eligible for it. Yep, you read that right. Once you fill out that 90 page form, they will send you a letter saying you are rated to receive 0% CCB, then you can apply for the CCR, another 90 page form which will bore you to tears of frustration and bewilderment with its complexity. Then if you have any back pay to claim, there is a further form to fill out at the end of the financial year, which is yet another 90 pages of the ins and outs of a duck's backside, with all sorts of totally irrelevant information I am sure you are dying to share with Centrelink. I was able to get all the forms from a FAO office after explaining in minute detail what I wanted to do. however I am still trying to regain the will to live after filling them out. I did all the forms in hard copy, so I am not sure about the online versions, someone else can probably fill you in. And yes, I have two degrees and it nearly drove me insane.
Hope that helps