The black keys are used to play what is known as sharp (#) and flat (b) notes and appear in groups of twos and threes. Look for the set of five black keys (1 group of 3 and one of 2) that are in the center of your piano.
Middle C is the white key to the left of the two black keys in the middle of the piano. Place finger 1 (your right thumb) on Middle C. If you go up and down the entire length of the piano you will notice that the key to the immediate left of any set of two black keys is a C. Take a little time to study the diagrams above and below again while matching the notes to the piano keys.