Generally you advance your city to increase the number of forge points (fps) you can collect from it each day. This can mean adding levels to forge point generating great buildings or adding buildings won from events or GE that make forge points.
Donation. To help construct a Great Building, simply visit a city of one of your friends, neighbors or guild-mates in which a Great Building construction is present, and click on the Great Building. You may now donate Forge Points, and also view which reward you will receive (if any) for your current donations.
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.
Blueprints for any Great Building can be obtained from contributing to that Great Building, if you finish a level in a reward position that gives them. Some reward positions on lower levels of Great Buildings only give medals, or Forge Points and medals.
And then select the goods and donate them the guild is happy about that gvg guilds need many goodsMoreAnd then select the goods and donate them the guild is happy about that gvg guilds need many goods for siege armies. And additional defense armies when fighting on the gvg. Map.
Forge points are mainly used to research technologies and upgrade Great Buildings.