The C sharp major seventh sharp eleventh chord is a 5-note chord consisting of the notes C#, E#, G#, B# and F##.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as C#maj#4.
Chords that are a superset of C#maj#4. The chords include more notes but always C#, E#, G#, B# and F##.
Chords that are a subset of C#maj#4. These contain less notes but all of them are included in C#maj#4.
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#maj#4 chord. Feel free to save or share the image as needed.