Your first step when listening to major and minor chords is to identify which chord you are hearing. Major chords sound happy and minor chords sound sad. This may sound childish but it works—try it and you will see. Once you know what kind of chord (also called “quality” of chord) you have (major or minor), see if you can hear the root. Let's use D minor for an example. Once you figure out the quality of the chord (minor) you can use your guitar to find out which note is the root D. Ear training involves the subtle art of hearing. There is no right or exact way to hear and you have to make judgments for yourself. When it comes down to it, ear training is an amazing art.