Step 1: does your development need approval?
Once a dwelling is built, you can carry out some minor building works, like garden sheds or carports, without needing approval from Council.
For existing commercial properties you can undertake certain changes in use or signage without consent. These are examples of exempt development.
You can undertake some larger but straightforward development as complying development, which is a combined Development Application and Construction Certificate process.
If your proposal is not exempt or complying development, you will need to submit a Development Application to Council.