Configuring white LEDs or knowing how to wire white LEDs is not difficult once you learn the required specs of these amazing device.
A white LED requires a minimum voltage of 3 volts DC to illuminate and needs up to 3.5 volts to light up optimally. So if your power supply is rated at this maximum level, you can use it directly to light a white LED.
However if your power supply generates more than this max voltage, you would require a series resistor with the LED, the value may be anywhere between 300 Ohms to 1K approximately.
The current required
If the LEDs are connected in series, the current remains constant but the voltage needs to match the total forward voltage of the series, that is if four LEDs are connected in series, the input supply would need to be around 4 * 3.5 = 14 volts @ 20 mA.
However if the LEDs are connected in parallel, the required voltage remains constant, but the current simply multiplies, for example, four LEDs in parallel would need a voltage of 3.5 and current of around 20 * 4 = 80 mA.
Every channel, whether connected in series or parallel must be accompanied with individual resistors for safeguarding the LEDs from damaging high currents.