Now bear with me here. I’m not a music theorist, so you musicians reading this may wince a little in places. This post will be very much of a layperson’s view of the whole major/minor issue and its relationship to the mood of a piece. I’m probably spelling out more than I need to in places; no intention is meant to insult anyone’s musical intelligence!
Where to begin? I guess with the question of what makes a key minor. Hoo boy. That question opens up a real kettle of fish of a different color. In modern tuning there are 7 major keys using sharps and 7 using flats (with some overlap, but I’m not going to get into that). There is also one key, C major, which has no flats or sharps. If you want to find the minor key that has the same key signature, that is, the same number of flats or sharps, as the major, then you count down three half steps and that’s the starting point for your relative minor scale. Even if you don’t play an instrument you probably have access to a keyboard of some sort. So start on middle C and play just the white keys up to the next C. There’s your C major scale.