That was a really long answer, but absolutely correct. To simplify, just sit at the piano and find the set of 2 black keys in the center of your piano or keyboard. D is located between the 2 black keys. Middle C is located to the left of D.
Moonlight Sonata: How to play this difficult piece full of black keys & triplets? Use large notes, lots of white space, & letters inside the note heads - easy!
Some of the best Bach well known pieces include those from the "Notebook for Anna Magdalena Bach." Among piano pieces, "Musette" is perhaps the most joyous!