How do I trade resources with other players?

At around stronghold level 13 you will be able to unlock the Trade Station building. Through this you can make requests for resource help or send resources to other members of your alliance.

You will also be able to tap on alliance members in the map and choose the trade option.

Upgrade the building to increase the amount you can send and also reduce the fee for each trade.

You can only trade your resources; stone, silver, crystal, and stone with alliance members. I was told by a mod to keep leaving feedback for the developers to add gift envelopes to share other items...I do it daily LOL