Goods are produced in goods buildings. They are unlocked through advancing in the technology tree. Goods buildings are usually very costly and require a large amount of population to be built. Enthusiastic population does not enhance the production from the goods buildings.
Click the "Market" icon in your toolbar to go to the trading market. Click on the "Create Offer" tab. Next to the words "Your Offers", select the good and the amount of that good that you wish to offer for trade.
Passive Bonus The Arc is a Great Building of the Future Era. It gives its owner an increase of contribution rewards when contributing to other players' Great Buildings and every 24 hours produces a quantity of each goods of the player's current era.
To buy Forge Points, you just click/tap on the plus sign next to the FP bar. A window will show giving you the option to buy FP with coins or Diamonds. To invite players that do not currently play, I believe you have to provide their email for Inno to send them an invitation.
Medals can be used for purchasing Victory Expansions. Also during the New Years event, we were able to trade Medals for random Blueprints.