Hello Teki,
In order to do that, you need to research the Trader technology. Then you have to build the Trader in your town. After that you will be able to trade with other players in the game.
However, keep in mind that the Trader is designed in such a way that you can trade only in your region. You won't be able to trade with somebody on the other corner of the map. A good way to bypass that is to join a fellowship. Being in a fellowship allows you to trade with all it's members without any restrictions.
Here's more information on how to use the Trader:
https://en.wiki.elvenar.com/index.php?title=Trader
