Guitar 3/4

Today I continued my efforts to try to learn "Wherefore Art Thou, Elvis?" by The Gaslight Anthem. The bridge of the song contains alternating major and minor chords. I have absolutely no idea how music theory works so I had to completely learn how to tell the difference between the two types of chords. A major chord is root, 4th, 5th; and a minor is root, 3rd, 5th. The song used nothing but D, E, and F# chords over and over again, but the spacing on the fingers was the hardest part. I'm sure if I had more time to spend on seriously studying music theory it would make more sense to me, as a half hour a week is simply not enough. I will try to spend more time practicing, but it's very hard to fit in a schedule.