Root on low E
244xxx
F♯5 is the F♯ power chord. Its notes are F♯ and C♯. It is the same chord as G♭5. No third means no major or minor quality. Mute unused strings carefully.
244xxx
x-9-11-11-x-x
Numbers show frets from the low E string to the high e string; x means don't play that string.
Every F♯ and C♯ on the first 12 frets. The filled dots are the root, F♯. Build your own shape from any nearby group.
Other F♯ chords
Other power chords