The E dominant ninth chord is a 5-note chord consisting of the notes E, G#, B, D and F#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as E9.
Chords that are a superset of E9. The chords include more notes but always E, G#, B, D and F#.
Chords that are a subset of E9. These contain less notes but all of them are included in E9.
In case you prefer a non-interactive variant of the chord chart, we've embedded a PNG image below that shows the notes for the the E9 chord. Feel free to save or share the image as needed.