Every fingering that fits a hand
x530
easy · no 5
a98a
hard
What is true of it
Fadd9 is F, A, C and G — 1, 3, 5 and 9 counted from F.
On an instrument that cannot reach all 4, the 5 goes first, in that order.
The easiest of the 2 fingerings below is x530: 2 fingers, held at the 3rd fret.
None of them uses an open string, so this chord moves up the neck unchanged — the same shape 1 fret higher is the chord a semitone above.
It leaves out the 5. 4 strings cannot carry 4 notes, and the 5 is the one this chord can lose without changing what it is.
1 string stays silent.
Where its notes are on the neck
The brass dots are F, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
Fadd9/A
2530
Fadd9/C
5530
Fadd9/G
0010
An inversion is the same chord with a different note lowest. The name changes to a slash name because the bass is what a listener hears as the foundation.