1 Advance to Feudal Age
In order to build a market and exchange resources, you first need to advance to Feudal Age.
2 Build a market
Before you can exchange resources you need to build a market. As soon as the market is built, the option becomes available.
3 Click the diplomacy icon
Click on the green leaf at the top right of the screen. Sending resources happens through the diplomacy screen.
4 Click on the resources
You will find the icons of the different resources listed next to the name of your Ally. Each click on one of the icons sends 100 of the resource you selected. (See How to Use Trade Carts in Age of Empires II)
5 Send to the right person
Note that you might be able to send resources to enemies as well if the diplomacy stance is not locked. Make sure you are sending the resources to your ally.
6 Hold shift to send more resources
Each click sends 100 resources. If you hold down shift, you will send 500 resources with each click. (See How to advance ages – Age of Empires 2)