• Hit one of the sides of the tuning fork on your knee, while holding the stem with your thumb and 1st finger.
• Take the base of the tuning fork and rest it on the guitar. Since your guitar is wood, it will vibrate at the pitch of the tuning fork. A 440 in this case.
• Play the harmonic at the 5th fret of the 5th string. You are going to pluck the string with your right hand 2nd finger, while still holding the base of the tuning fork against the guitar. (that is the tricky part at first)
• Tune that harmonic to match the pitch of the tuning fork.
• You with then tune all of the other strings to the 5th string.

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