The next components to install are the LEDs. Light emitting diodes are used in all sorts of electronics to provide bright, different colored lights.

Note that the two leads are different lengths. Since an LED is a diode, it only allows current to travel in one direction, so it is important to install the correct lead in the correct hole.

The four LEDs belong in each of the four terminals marked LD1 through LD4.

When installing the LEDs, insert the shorter of the two leads into the hole next to the flat part of the printed circle.