Trade is managed via the trade tab on the finance panel, where details of the current prices of all resources produced across your territory are displayed along with information about how these are exported to our trade partners - together with the profit made from exporting to each one. Also shown are the resources available to you, both those you have gained from your trade partners and those you are yet to acquire. Certain advanced units and buildings require access to these resources before they can be recruited or constructed.
A trade post is the means through which you can trade with foreign powers - the nanban, or southern barbarians - who do not otherwise appear in the game. Trade posts are positioned out to sea away from the coastline of Japan. In order to begin nanban trade, build a trade ship and send it to a trade post icon by right-clicking on it. Trading commences when your trade vessel's flag flashes with the yellow coin graphic.