Is there any way to hook-up a led to the microcontroler? If so, how?

Yes, but it depends on the LED you select. We give you the specifications of the Vex Controller at http://www.vexlabs.com/vex-robotics-design-system.shtml. You must select your LED to be compatible with the Vex outputs as you would with any Non-Vex component you connect to the Vex Controller. The pin out for wiring is also on this page.