How to use the /fill command with black wool or oak wooden planks?
For black wool:
/fill X1 Y1 Z1 X2 Y2 Z2 wool 15
The value after the block type is its data value, which is 15 for back wool.
For oak planks
/fill X1 Y1 Z1 X2 Y2 Z2 planks
As of Minecraft 1.13, filling areas with black wool no longer requires the use of cryptic numbers:
/fill X1 Y1 X1 X2 Y2 X2 black_wool