understanding global trade

Towers of ilium ventures, once again, into the festering swamp of economic and business theory. Here is a brief explanation of trade between nations:
Nation A manufactures (or mines) heaps and heaps of useful things--like plastic cups or iron ore. Because it has more plastic cups or iron ore than its own people want or use it puts these items on boats and sends them across the ocean to Nation B. Now, Nation B might have iron ore of its own, and might have factories that make plastic cups, but in both cases it's easier to get them from Nation A. So, how does Nation B pay Nation A for all this stuff? It's simple; Nation B has a bunch of people at computers send some people in Nation A an electronic message full of ones and zeros which it calls "money." The people in Nation A can put this money in banks or exchange it amongst themselves for haircuts and vinyl siding and rock concerts. The ones and zeros keep on moving around--some even come back to Nation B when people from Nation A travel over to see the vast collections of plastic cups and piles of iron ore baking in the sun. Everything works as long as you have enough ones and zeros. If you happen to run out of iron ore or plastic cups, it's okay--switch to paper cups and start recycling some of the junk you built with the iron ore or use alternative materials like carbon fiber and aluminum.

This all makes sense. You just have to keep everything moving.