I am Nepali currently living in Australia as a Permanent Residence

Asmita, you should send your application to HK immigration department. Below is the postal address:
Receipt and Despatch Sub-unit
HK Immigration Department
2/F, Immigration Tower
7 Gloucester Road
Wan Chai, HK
The required documents for tourist entry permit contain copy of your passport, the application form attached with a bareheaded color photo, proof of your financial support, transportation arrangement and proof of the proposed visit in the next destination.