For major scales, the note names, when descending, are just the reverse of the ascending names true or false

c, d, e, f, g, a, b, and c.

sometimes western music will also use solfege. the names of these are do ra me fa sol la si (or ti) and do.

to indicate a note a half step higher or lower then the original note, you would say c # (for a half a step above c) or bb (for half a step below b)