How and can you get German work visa if you are an Australian citizen?

Please tell me as much details would be really appreciated.Do I hjave to find a job and apply for a visa,or I just have to go to Germany and do it?

You would need to have a job ahead of time and that company would help you with your work visa. You can look online or enter Germany on a tourist visa and look around personally. Ask the Embassy for specifics.

Don't you basically apply for it? At a German Embassy because that's what you do for any kind of visa you want to apply for. Right?

If you're under 30 the easiest way would be a work&holiday visa.
If you're older a job offer would be very helpful. In any case you need a visa first before being allowed to work (legally). Since you didn't provide any details you might have a look yourself on the official german site trying to find the information you need:
http://www.auswaertiges-amt.de/diplo/en/...

Getting enrolled at a german university (tuition might have been raised to about 500 EUR per semester in the mean time) might also offer you a chance to work part time and/or during the semester breaks. Then have a look at the universities' home pages.