Some people buy the physical products and then ship out domestically.
Others buy directly from the supplier, put in the customers details and then have it shipped.
Aliexpress suppliers can be quite unreliable, either in terms of sending the item, or the quality of the product, so it's up to you whether or not you're willing to take the chance. There are plenty of people who push this method of selling as a way to get rich, but in reality, if a supplier is sending low quality goods out, or packages don't turn up, you will have lots of complaints, negs and requests for refunds.
Also, if you get the supplier to ship to the customer directly, the packaging has Chinese customs forms on it, so the buyer will probably get irritated if they're buying from an Aussie seller, but the package comes from China.
Packages can take a long time to get to the customer - usually far longer than sending something domestically.
It would be better if you were to buy from Aliexpress directly as you can then check the quality and see how long it takes, but you have to be prepared to physically hold all the stock until you sell it.
Since you have zero selling experience on Ebay, you're going to be out of your depth very quickly.
