The Australian Federation Flag is the first official flag for the British colonies in the Australian continent. This was created in the 1830's, as at the origine, precisely in 1831 by the captain Jacob Gronow, master of the Harbour of Port Jackson (the former name of the town of Sydney);
this was the flag for the main colony, the New South Wales. Let's remind that in 1830, the colony of New South Wales is bigger than the current federated State in Australia, but contained Queensland, Victoria, South Australia and Northern Territory (sure the ACT). For a short time, even New Zealand (from 1840 to 1841). This flag has a centre blue cross with the Southern Cross inside made of five Commonwealth stars. In the canton, there is the Union Jack. It has become popular in the 1880's and has been popular as the real flag of Australia in the minds of Australian until the 1920's. After the Red/Blue Ensign took the predominance.
If you want to have a look on the Australian Federation Flag: http://en.wikipedia.org/wiki/Australian_Federation_Flag So I took this flag as model , I have removed the Union Jack and coloured by green and yellow alternatively the white parts and have let a thin white space between the coloured parts and the blue cross.