There are many types of chords that come from the ‘dominant seventh chord’-family.

All these chords can be used in swing- and jump-blues.

These chords all have in common that they use the formula 1-3-5-b7.

By ading notes to this formula, we color the chord.
The most commonly used colors in swing- and jump-blues are 9th and 13th.

A ninth chord has the formula : 1-3-5-b7-9

The 9th can be found one whole note (2 frets) above the root.

If we were to do this on a C root,  the notes we find are:
C – E – G – Bb and D.

These notes played together form a C9 chord


Again: there are many 9th-chord shapes we can find on the fretboard.
Look at the overview of chords at the back of this book/website for some examples.