With little instruction on my part, my Nephew managed to lay out this circuit, wire up all LEDs with the correct polarity, including 330-Ohm resistors wired inline on each diode.
After a few minutes of studying some sample Arduino Code, he started experimenting around and came up with this. Not bad at all. :-)
Next step on his wish list of lighting accomplishments is to control the individual brightness of the LEDs.
For the technically inclined: It's pretty easy to do if you switch from a Digital I/O pin to a PWM (Pulse Width Modulation) pin, and use AnalogWrite() -- but I'm holding off on that lesson for a little while. Pulse Width Modulation and the topic of Duty Cycles are best explained with an Oscilloscope alongside the LED changing brightness, IMHO, and I'm hoping my new 'scope arrives in time to go over that lesson in another week.
For now, the Nephew is studying up on the Arduino programming language -- particularly all about loops and program structure.
'Definitely proud of the Nephew. :-)