First of all, please do not make threads only using capital letters. It's against the Global Forum Rules. I edited the headline.

(If you haven't read them yet, please do so before posting, thank you.)
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Now, I am not exactly sure what it is about the marketplace that you don't understand. So I am just going to give you some general links, hoping that your answer is among them. (If it is not, please post again and go into detail about what you don't understand.)

- General Information on the marketplace
- Guide on how to move ressources between your own cities
- marketplace in the Game Guide and how to trade with other players