How do i tune a guitar using harmonics? what are pitch harmonics?!

How do i tune a guitar using harmonics? what are pitch harmonics?

1st string 5 to second string 7(using harmonics of course).second str. 5 to 3rd str. 7; 3rd str. 5 to 4th str. 7; 4th string 4 to 5th str. 5; 5th str. 5 to 6th str. 7. Pinch harmonics are when you ply a note with your pick, a roll your wrist, so the side of you thumb grazes the string, just barely, stopping the primary movement of the string, but allowing the string to still vibrate the harmonics of the pitch( it makes an electric with distortion squeal. You can probably find a good demo on you tube.