When you press the [Task] button it will bring up a task menu. This menu has ten possible user defined tasks to choose from. You design the task. You can design a task to beam up or down X number of Neutronium, Duranium, Tritanium, Molybdenum, Supplies, Colonists, Megacredits and Torps / Fighters. The X represents the amount you enter in the black box under the Beam UP / Beam DOWN radio buttons (these are the buttons on the task menu that you select to help define the task). Green items are going to be beamed up from the planet and red items are going to be beamed down to the planet.
The above task has been named Beam Down Colonists by the player. This task will beam 100kt fuel up from the planets surface while beaming down 100kt of Molybdenum, 100kt of Supplies, 100 clans of colonists and 300 Megacredits.