Or you just want to give some tagpoints :-)

http://www.imperialconflict.com/guide/

you will find this here (your answer is at the bottem):
The market form is very easy to use. All you have to do is choose the resource you wish to buy or sell. Enter in the price of which you want to buy, or sell. Fill in the amount of that resource you wish to buy or sell and send this order to the trader. If you need the resource right away, you should buy at the sell price and you will get it immediately. If you want it for cheaper, buy it at a lower price and a bid gets placed, but then you'll have to wait until someone sells at this price. The Market Advisor, Jennifer will update you in the HQ on what you have bought, or sold.
If you have any bids placed on the market, you can, at any time, cancel them by using the withdraw bid function. There is a 10% fee for withdrawing bids

The market has a limit you can sell resources at, that limit is 50 gc. The reason for this is to stop market abusers from selling resources at astronomical prices, then using that money to have an unfair advantage. In addition, each bid can contain a maximum of 2,147,483,647 units: if any more units are sent they disappear.

A 2% Market Fee on all sell bids are taken by the family's market agent.