The F sharp altered chord is a 4-note chord consisting of the notes F#, A#, E and G.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as F#alt7.
Chords that are a superset of F#alt7. The chords include more notes but always F#, A#, E and G.
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 F#alt7 chord. Feel free to save or share the image as needed.