Hey there! Welcome to the wonderful world of Pinch Harmonics.
If you listen to the playing of guitarists such as Zakk Wylde(Ozzy Osbourne), Billy Gibbons(ZZTop) or more recent players such as Thomas Blug, you will hear pinch harmonics in abundance.
The technique of playing pinch harmonics is very similar to the technique of natural harmonics where we create what is called a 'node'(dead spot) on the string by lightly touching it with the left hand fingers. This has the affect of dividing the string in two either side of the node resulting in a natural harmonic.
The most common positions for playing natural harmonics are at the 12th, 7th and 5th frets.
With pinch harmonics, we use a combination of left hand fully fretted notes with the right hand thumb and pick. Essentially, instead of creating the node with the left hand, the right hand thumb takes on this responsibility by lightly touching the string in front of the pick while the left hand frets the note, c in this case, on the 3rd string 5th fret.
If you are new to this technique, it may be a rather hit and miss affair to begin with until you get a good feel for where the harmonics occur between the neck and bridge for any given note. Remember that changing the left hand fretted note will result in a change of position for the correct harmonics too.
It is a good idea, once you have the basic technique down, to experiment to find out where the harmonics do occur. Once you find your favourite sounding harmonics, make a note of where it occurs so that you can be more accurate with your positioning.
OK guys, happy squealing!