If a chord has four notes in it you can create 3 inversions from it. The root position chord does not count as an inversion.
Below are the notes of the C major7 chord and their inversion.
This type of thing is much easier to see on the piano then on the guitar due to the way the notes are laid out. In the examples below notice how the inversions simply move up the keyboard one note at a time.
On the guitar it is difficult to play a proper inversion with the notes in ascending order so we mainly focus on having the correct chord tone in the bass.