An inversion is a chord that starts with a note other than the
root as the first. a C chord is made up of the notes C, E, and G.
If the chord is played as the notes C, D, and G it is not inverted.
If the chorde is played E, G, C, this is the first inversion,
If it is played G, C, E, this is the second inversion. That is pretty much all
their is to inversions. As you build more complex chords, Csus7b5, there are
more inversions. If you look at a keyboard, it is much easier to
see than it is on a guitar.