The Market is where you can trade and transfer resources to other people. You can purchase resources in the market, or you can send resources to another allied league mate from your league. The Market is divided into two parts; The Market, and the Black Market. Leveling the Market will also raise the amount of resource that you are able to send to your league members.
In order to buy resources in the Market, you will need to fill out your ammount and the prices that others are selling their resources for. As seen in the picture below, you are not looking for the "Buy" option to buy resources. You are looking for the 'Sell' in order to buy. So choose which sell price you would like, and enter that amount on the right side, as seen below. Then put in the price of the resource the person is selling them for, as seen below. You do not have to purchase the entire quantity that they are selling. Notice there are two areas here. The bright market and the dark market. You cannot buy stone in the dark section, so you need to go to the bright section in order to buy any stone. The brights cannot buy any Iron on their side, so they have to go to the dark side in order to purchase iron.
When you have made a successful purchase of goods, then you can go to your deal tab to see the transaction and the time it takes to get to your city. As seen below.
In the Black Market, you are able to sell your resources for gold. As seen below, you can see that the Black Market has a policy added with it. Using the policy requres 5 Magic Potions, or 5 Diamonds. This will guarantee that your purchase is successful. Without this policy, there is a very high possibility that your transaction will fail. The success rate is very low, but it is always nice to be able to sell your resources for some extra gold. Your price is always 0.2 in the black market, and cannot be changed.