For example:
* If talking about how a word is written: You might use a phrase involving words like γράφω (grafo - I write), ορθογραφία (orthographia - orthography/spelling), or γράμματα (grammata - letters). For instance, you could say something like: "Πώς γράφεται αυτή η λέξη;" (Pos grafetai afti i lexi?) which means "How is this word written?" This is the closest equivalent to asking how a word is spelled.
* If talking about the act of spelling aloud: You might use a phrase involving προφέρω (profero - I pronounce) or αναφέρω (anafero - I mention/refer to) in combination with γράμματα (grammata - letters).
Therefore, there's no single Greek spelling for "spelled," but the appropriate phrase depends on what you're trying to convey.