I would like to report online my income to centrelink

Only if your trolling.

Ronnie,
Why are you asking this on the Fixya website? Just call your Centrelink provider and discuss with them.

hi Andrew.
this is all i can find out.

1. Step 1: sign in and access your income and assets details. Sign into myGov. Select your Centrelink online account to access your homepage and full menu options. ...
2. Step 2: tell us what income and assets details you're updating. First, you need to tell us the date the income or asset change occurred.

Update your income and assets details using your Centrelink online ...

or check this link out.
how to notify centrelink of change of circumstances Google Search

I believe so. Centrelink requires income reports. However, that can be done via the web or by phone. If your income was zero, you would still need to report that "change in income" to Centrelink in order to continue receiving any benefits from Centrelink. Moreover, if you can not meet any of the particular activity requirements, you need to indicate so to Centrelink. You will very likely have to present the medical certificates as well or else send such via an attachment via the reporting page. That said, you will very likely be freed from having to meet an activity requirement during the time covered by your medical certificate.l The MyGov website offers a single password entrance to a variety of government agencies provided you opt to link those sites to MyGov.

keep trying or try customer assistance with the application site

Submit your Centrelink documents online

Centrelink online accounts

https://www.centrelink.gov.au/LoginServices/source/portal/Login.jsp?finalURL=http%3A%2F%2Fmyaccount.humanservices.gwy%2FLoginServices%2FAuthenticate.do

You will very likely want a MyGov account to which you can add various departments like Centrelink and reach them all via that one site. The is also an Express app available for phones which may allow you to submit information. The pages above should supply you with relevant information. I think you can also report by phone call via a "robotic phone call system." This CAN number is on the card Centrelink provided you.