File:Space Trader Trading screen.jpg

This image is taken from the official promotional materials - see http://store.steampowered.com/app/11240/

Within the screenshot:
 * The top shows the menu for accessing other planets, inventory, the bank, options and exiting.
 * The left shows the list of available contacts, allowing you to teleport instantly to them. (If you completed the mission, you can click the retire button at the bottom left.)
 * The center shows which items can be bought or sold. In an item line, you see the commodity name, the current cost, a star (if it's a good deal at the time), the change since last travel, and the price-index percentage (0% is low, 100% is high, although it sometimes extends past that.)
 * The right lets you confirm the purchase.