Chet Atkins was an absolute master of fingerstyle guitar. To play his rendition of “Imagine” by John Lennon pick the notes on the low E string and A string with your thumb, pick the notes on the D string with your 1st finger, pluck the notes in the G string with your 2nd finger, pluck on the B string with your 3rd finger, and pluck on the high E string with your 4th finger.