One thing I didn’t mention on “The 3 Basic Chords” post is that, to play a song using chords, usually the chords are played with the right hand, while the left hand plays the “bass” notes.
A question one may ask is, “then with which hand is the melody played?” There are 2 answers to this question. Firstly, you can sing the melody. 
Secondly, you can play the melody with the right hand also. You will find that after a while, when you are familiar with playing chords and especially the different ways to combine chords, it is indeed much easier to play the melody than if you didn’t know the chords. But that will take time and experience. Let’s leave this till much later.
For the moment, let’s come back to the question about what we should play on the left hand while the right hand is playing a chord. The simplest thing to play on your left hand is just this – one note. Period.
That is, if the chord on the right hand is C, then play the C note on the left hand. Similarly, if the chord on the right hand is an F, then simply play the F note on the left hand. You can choose to play just one note or to play an octave. Put simply, it means 2 “doe” notes that are separated by one set of “re”, “me”, “fa”, “so”, “la”, “ti” notes in between. Figure 1 below shows the C octave. Note that 2 notes are played at the same time, a lower C and a higher C.
Figure 1: C octave
Does it matter which lower C and which higher C your left hand should be playing? That’s a good question. In fact, the same question should be asked about the chord on the right hand, i.e., how far on the right of the piano/keyboard should you place your right hand to play a chord? I know this may not sound like a good answer but I can only say “it depends”! It’s a matter of how it sounds to you. It’s like adjusting the treble and bass levels on any of your sound systems, be it a radio, mp3 player, car stereo system, or a home hi-fi. Different people like different settings. So if you find the bass notes you play with the left hand are too “bassy”, then shift your hands further to the right to play higher notes. The same principle applies for the chord on the right hand.
Another thing you can do on your left hand is to play what some call “broken chords”. But I think I will reserve this for another lesson.
So much for now.
