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.
Drop D Tuning
This song is in drop D tuning. In drop D tuning the low E string
is tuned down one whole step to D. This enables the guitarist to play
power chords with a single finger. If your favorite band uses drop
D tuning and you want to experiment with this tuning, by all means
do so. What ever you do, don't learn the guitar in drop D tuning-you'll
get all mixed up.
To tune your guitar to drop D tuning, first make sure your tuned
to standard tuning. Then you'll want to tune your low E string down
two steps to D (we drop it down one step, hence the name). See the
picture below. You can use the audio clip below to tune your low E
string to D for drop D tuning.