Use the repeating groups of two and three black keys to find your way around the piano.
Find the repeating pattern
Find a group of two black keys
Look for two neighboring black keys with a gap on either side. Find that group in more than one place.
Find a group of three
Now find three neighboring black keys. Alternate between finding groups of two and groups of three.
Find C from the pattern
C is the white key immediately to the left of a group of two black keys. Find several Cs without counting from the end of the keyboard.
The pattern repeats across the keyboard. Some keyboards begin or end partway through a group, so use a complete group near the middle while learning. Black keys are part of the same musical system as white keys, not a separate advanced instrument.