Well you can do it a few different ways.
You can technically just go to Japan and buy a car and have it shipped. When it gets here you will need to clear it through customs and pay duty etc on it. This is probably the worst way to do it however as you probably wont get such a great deal on the car, and you will have difficulty getting the paperwork done and getting the car on the boat yourself.
The other way is to use an import broker, they deal with finding the car for you while you stay home. They speak with buyers who attend the auctions and bid on behalf of their customers. They can also source a few cars from various wholesale yards they have dealings with.
Probably the most talked about import brokers on this forum are Prestige Motorsport and J-Spec. I'm not endorsing them although many do.
Another way to do it is to cut out the import broker and talk to the buyers in Japan yourself, some of them speak english and specifically deal with overseas customers all the time. You can save the import broker fee this way. The problem with this is that you dont reach as many buyers as you would if you used an import broker. You may take longer to find a car.
Since you're such newbie at this i suggest you do a load more research on it, read the FAQ's and such on the J-Spec and Prestige websites. There is no hard answer on which way you should go when importing a car. It's kind of a personal decision where you weigh the risks and costs against the benefits of each method.
http://www.prestigemotorsports.com.au/
http://www.j-spec.com.au/