This isn't a quick, cheap or easy process. For licensed trades, more so.
My advice would be to speak to a good registered migration agent. But start with lots of reading at Homeaffairs.gov.au and look at the 189, 190 and 491 visas. This will start to give you some idea.
In essence, first, you need an occupation on one of the skilled occupation lists, which I believe your is.
Second, you need a skills assessment. This will be a assessment of your qualifications, experience and potentially a practical and theory exam.
Third, you need sufficient points. This can be a funny area as it can be a competition for the highest points and so most people find they need to take English exams such as ILETS to claim points for English.
Once you have all these, you can lodge an expression of interest (eoi). This is where the competition can start. You then wait to be invited.
Then medical and police checks will be requested.
Then visa.
Staet to finish, allow about a year.
But. On arrival, you will not have a license to be a plumber. To obtain this will vary on state. But, may include some college courses and working for a while as a trade assistant - a bit like an apprentice