In the last two lessons I showed you the basic Major and Minor chords. Get to know these very well. You should be able to change between any of these chords very quickly. The only way to get good at them is with practice and memorization, so be sure to work hard at those.
Minor Chords: You will usually hear minor chords in 'sadder' sounding music. That does not mean that all sad music uses minor chords. Or that any happy songs can't have minor chords.
Major Chords: You will generally hear these chords in 'happier' upbeat sounding songs.
HOWEVER:
Playing guitar is all in what you hear, so this is just a basis for todays music. Feel free to use these however you want. You do not have to use only minor or major chords at one time. I would suggest that you don't do that.
That's all for now. Perhaps the next lesson will be on keys. Don't know for sure yet.