CFDs or Contracts For Difference are mostly a trading instrument.
You can read the CFD definition in the Theory section - here.
CFDs are becoming more and more popular trading vehicle in Australia in the recent years. This could be a result of accumulated wealth during the boom years 2003-2008.
There are a few providers offering similar conditions of trade, access to financial markets, and fees. Many of them also provide informative introductory seminars on trading in general and their products.
Some of them have introductory programs to get you going in the CFD trading business, as it is called.
There are web sites with useful forums and CFD provider comparison and ranking, based on votes from the site users.
CFD providers' accounts can be a valuable source of information. Many of them provide a direct access to a number of prices ranging from world indices, shares, commodities and so on. Some providers will offer the trading platform for free while some charge a fee. Fee is usually paid for data feed but some provide it for free, too.