Simply put, a broker is a company that allows you to buy and sell currencies. It acts as an intermediary between buyers and sellers.
Once you’ve got used to understanding how a demo account works and how the software works, you can trade live, i.e. with real money. You don’t need thousands of dollars upfront, it can be as little as a $100 of initial investment, just to get started.
In the past, before the internet age, Forex trading was limited to the big boys, such as the banks. Now however, with the arrival of the internet, retail forex brokers have opened their doors for anyone. So now, individuals, companies, other firms & institutions can easily buy and sell currencies, and make a living from it.
Indeed, one of the advantages of the foreign exchange market is that it allows international trade and investment, helping businesses convert one currency to another. For example, it permits a U.S. business to import European goods and pay Euros, even though the business's income is in U.S. dollars.
There are many different forex brokers across the globe. And as mentioned before, you don’t have to visit them to register with them – it’s all done over the internet. Just register your details, and make a deposit of how much you want to trade. To be honest it doesn’t really matter which broker you deal with, as long as they’re regulated by a financial authority (for example the NFA in the United States, and the FSA in the United Kingdom).