glotech,
Unless you plan to make the LEDs blink, turn on and off at different times, or have variable brightness the only parts you'll need will be the LEDs, some resistors, and a power source.
The sizing of resistors is easy. The resistors job is to limit the flow of current. The LED brightness will vary with the amount of current that's flowing through it. The more current, the brighter it is. The less current, the dimmer. This is only true up to a point as the LED can only withstand a certain amount of current before it burns out. That maximum current can usually be found in the data sheet. Just for the sake of this example let's say it is 25 mA or .025 A. The maximum current isn't the only thing you need to know. You also need to know what the forward voltage drop of the LED is. This is different for different color LEDs and once again ca be found in the LED's data sheet but for this example let's say it's 2V.
Let's use this simple circuit for the example:
So far we have:
Maximum current: I = .025 A
Forward Voltage: Vf = 2V
Next we need to determine what the voltage drop will be across the resistor. If the supply voltage is 5V and the voltage drop across the LED is 2V then the remainder:
5 - 2 = 3V must be dropped by the resistor.
The current going through the resistor and the LED will be the same because they are in series.
We use Ohm's law:
V= IR to find what value the resistor should be.
Solved for R:
R = V/I
R = 3/.025 = 120Ω
Remember that this resistance value was calculated for the maximum allowed current. To be conservative and to extend the life of the LED it would be best to bump it up a little. If you want a dimmer LED, bump it up a little more.