Currency trading is refered to as forex or FX (short for foreign exchange). It takes 3-5 years to learn to be profitable and most people lose all of their money within 3-6 months because it's highly leveraged, at around 100x. Before you learn about trading, you should learn about the educators. Here's a good video to watch. Anton Kreil is a pretty well known trader.
Send some specific questions and maybe I can direct you a little more.