The Keyboard – the black and white keys which are pressed down by the player to make sounds.
The white Keys, like the notes on the stave, are named after the first seven letters of the alphabet A, B, C, D, E, F and G and go from left to right, repeating. After G, the next white note to the right is another A.
To find D, look for two black notes together (not in a group of 3), the white note inbetween is D.