Your Qatari license cannot be automatically exchanged for an Australian one. You have to take a test which is in two parts, one a multiple choice examination and the other a practical driving test.
Each state has slightly different rules but for example in Queensland check out:
http://www.transport.qld.gov.au/Home/Licensing/Driver_licence/Getting_a_...
Some overseas licenses are able to be used if you are a permanent resident, but check on the above site for Queensland. For other states just Google "Australian driving licenses"