The D sharp dominant flat ninth chord is a 5-note chord consisting of the notes D#, F##, A#, C# and E.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as D#7b9.
Chords that are a subset of D#7b9. These contain less notes but all of them are included in D#7b9.
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 D#7b9 chord. Feel free to save or share the image as needed.