The wood could be a 2 x4, a piece of molding or even an old log - you're only limited by your imagination.
Decide how many tealights you want in your display and then do a little math to evenly space and mark where you want to drill your holes.
Tealights are a half an inch tall, I like the metal casing to be completely covered by the surrounding wood so the hole has to be at least a half an inch deep, you can mark your bit with a piece of tape at a half inch to give you a visual while you're drilling.
Also, watch the depth of your wood, if it is less than an inch you will break through the bottom with your spade bit so you'll want to elevate your wood to protect the surface underneath.
Once you've drilled out all of the holes, vacuum up the wood shavings and add some tealights and light them up - remember to never leave lit candles unattended.
I'm Mrs. Fixit and it's just that simple!