Trade and transport resources here. Upgrade can increase trading capacity.
Resources can be transported to your own cities and to those in your league by choosing a city on the World screen and selecting "Transport" or from the transport tab if you know the coordinates of your destination city.
Normal Market Each faction can sell anonymously, three resource types on the market to other player within their faction on the normal market and can buy from either factions Normal Market. There is a 5% commission for buying and selling within your faction and a 10% commission for buying from the rival faction. Bright deals in crops, wood and stone. Dark deals in crops, wood and iron. There may be a wait time for a deal to be reached. The available deals are displayed and you can then either accept on of the current deals or submit your own deal and wait for someone to accept it. You will get an email every time one of your deals is accepted and the gold or resources will be added to the cities total that the deal originated from.
Black Market Anyone can buy or sell resources on either faction's black market. The price is always 0.2 gold per resource for both buying and selling. The Black Market's risk is that your offer may be stolen and you loose the gold/resources you offered, but the reward is that every deal is instant. To safeguard against loosing gold/resources you can purchase insurance for a cost of five magic potions or diamonds.