The C sharp minor ninth chord is a 5-note chord consisting of the notes C#, E, G#, B and D#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as C#m9.
Chords that are a superset of C#m9. The chords include more notes but always C#, E, G#, B and D#.
Chords that are a subset of C#m9. These contain less notes but all of them are included in C#m9.
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 C#m9 chord. Feel free to save or share the image as needed.