That all depends on what you're trying to say in Greek. Your best bet would be to find a translator, either online or a book, and go from there.
They were the first people to write the alphabet. The Ancient Greek's
slate
noo noo sticks
Ashley-ΑΣΗΛΕΨ
An oracle
Apherdite i think ?
Polyphemus would look like this in Greek: Πολύφημος
The Ancient Greek poet Homer.
ΞΟΛΒΨ Hope this helps!
ΣΕΝΝΙΦΕΡ Please note, however, that there is no "J" in the ancient greek alphabet, so it was replaced with the letter it would have been in ancient greek; "Sigma" or "S".
Παρθενών [Parthenon] (Ancient Greek) , Παρθενώνας [Parthenonas] (Modern Greek)
ΠΡΙΝΞΕΣΣ Hope this helps!