Look for and identify the set of two black keys together that is nearest to the middle of the keyboard. The white key immediately to the left of these two black keys is "Middle C."
Move one key to the left from Middle C. That key is letter "B," with the next key to the left being letter "A."
Move toward the right from Middle C, labeling each white key with the next letter of the alphabet. You'll find "D," then "E," then "F" and then "G." After arriving at "G," the sequence begins again with "A," "B," "C," etc.