So I do politics at uni so they have gone over this a lot and it's a bit complicated at first so I thought I'd share.
Yes you have to show up (or at least do early/absent/online) and it is between 8 am and 6pm, they tick you off and give you the ballot.
If you wish you can make the vote informal or do a donkey vote but you might as well do it properly.
House of Representatives
This is where KRudd and Abbott chill out, its the lower house and the main thing for laws.
We use an Alternative Vote/Preferential System, which means we rank ALL candidates, eg,
When they are counting the vote it comes in multiple rounds.
1st round use all the first preferences, if someone gets 50 percent of the vote plus 1 in your electorate then they win and represent you. If they don't they find out who got the lowest amount of votes and that person all the people who voted for them they take there no 2 options and assign them to their second preferences and so on until someone has 50 percent plus 1.
Government is made by whichever party can get the most support in parliament.
The senate is a bit more difficult as it is easier for minor parties because it is proportional. (Be thankful we live in SA and not the Eastern states as we only have 73 candidates unlike there +100.
You have a few options:
Above the line (95% of Australians do this), you put a number one in the box of your preferred party above the line, as they have registered preference flows with the commission. So check these as the votes may not go where you expect.
Below the line (arguably more democratic), you have to number from 1 to 73 for ALL candidates but you can make 3 mistakes and it still counts as formal. You can also put a number above the line and they will only use that if you below the line is informal.
We are electing 6 senators and they need 14.4% of the vote to get elected, that's called a quote. So Labor and Liberal will normally get two quotas each. Preferences are also distributed here but it's a bit more complicated and works similar to the lower house.
They won't know the definite senate result for a few days and they start there job next year.
The U.K. uses First Past the post where it is simply the most popular meaning someone can get in with only 30 percent support the most popular wins, In Australia this system means a broader support and the least unpopular wins.
Use this to organise your preferences, check policies and candidates http://www.belowtheline.org.au/
And this to see where your above the line preferences will go http://www.abc.net.au/news/federal-e.../guide/gtv/sa/