This is how you play the G/C chord on guitar.
Tune your guitar
Tune your guitar to the standard tuning of EADGBe
Index finger: 3rd fret, 5th string.
Place your index finger on the 3rd fret of the 5th string.
Middle finger: 3rd fret, 1st string.
Place your middle finger on the 3rd fret of the 1st string.
Play chord.
Strum all strings, except the 6th string.
https://guvnaguitars.com/chord/g-over-c/
