Every fingering that fits a hand
0252
easy
cbac
hard
What is true of it
Gadd9 is G, B, D and A — 1, 3, 5 and 9 counted from G.
On an instrument that cannot reach all 4, the 5 goes first, in that order.
The easiest of the 2 fingerings below is 0252: 3 fingers, held at the 2nd 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.
Where its notes are on the neck
The brass dots are G, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
Gadd9/B
4230
Gadd9/D
797a
Gadd9/A
2232
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.