Money flows based on supply and demand. It may be a supply and demand for return on investment, such as interest rates. It can also be supply and demand for a commodity such as wheat (food for humans), soy beans (food for humans or feed for animals), corn (food, feed and energy if used for ethanol), gold (inflationary hedge, jewelery, dentistry, and electronics), oil (power, gasoline, fertilizer, plastics, and fabrics) and such.
Many economies have some of the resources they need, but none have all of them. They reach outside of their borders for the commodities they need: to Canada for oil, to Australia for gold, to the United States for corn, to Brazil for soy beans, for example. When lack of supply increases demand it will drive up the value of the currency for the economy, which exports the commodity, because the commodity is purchased with the local currency. Supply and demand at its best!
So where do you start as a new forex trader? I suggest the USD.