Take note of the keyboard layout. There are white keys and black keys. There are two major groups of keys: one made up of three white keys with two black keys in between each, the other made up of four white keys with three black keys in between each. The first white key of the first group, located to the left of the first black key, is called "C."
Familiarize yourself with whole and half steps. Moving from one key to the immediate next---such as a white key to a black key, or to a white key if there is no black key in between---is called a "half step." Skipping a key---such as going from a white key to another while skipping the black key in between, or moving from a white key to a black key if there is a single white key in between---is called a "whole step."
Find Middle C. This is the C that is located directly in the middle of the keyboard. If you're using an 88-key piano, Middle C is the 40th note from the lowest note, or the fourth C from the bottom.
Learn the notes of a basic, major scale, such as C Major. For a C Major scale, you'll play every white key one at a time, starting on C, working your way up to the next C. In doing so, you'll play the following notes: C, D, E, F, G, A, B, C.
Memorize the stepping sequence of the major scale. From C to D is a whole step because you skip a key---the black one in between. From E to F is a half step because there are no keys to skip. Thus, the stepping sequence of the major scale is, moving from the first note of C:, whole (D), whole (E), half (F), whole (G), whole (A) whole (B) half (C). Thus, two whole steps, one half, three whole, and one half step is the stepping sequence for a major scale.
Assign each note of the major scale a number, starting with the first. Thus, C, D, E, F, G, A, B, C will also be known as 1, 2, 3, 4, 5, 6, 7, 8. These numbers are called intervals. The eighth interval is also called an "octave."
Play a chord by using your thumb on C, your middle finger on E, and your pinky on G. A chord is when you play two or more notes simultaneously, so play these notes together. This is a C Major triad in root position. This triad uses the first, third and fifth interval of the scale.
Try playing those same notes in different orders: E, G, and C using the thumb, index finger and pinky; G, C, and E, using the thumb, middle finger, and pinky. These are the first and second inversions, respectively, for the same C Major triad.
Play a C minor chord in root position by lowering the third interval by a half-step, playing the black key between the D and E. This is called "flatting," and you will be playing E flat instead of E.
Try playing those same notes in different orders: E flat, G, and C using the thumb, index finger, and pinky; G, C and E flat, using the thumb, middle finger and pinky. These are the first and second inversions, respectively, for the same C minor triad.