Here is some information on how to access the keyboard...and links for how the letters are pronounced. Try them out. Go slowly. You are at the beginning.
HOW TO GET THE GREEK KEYBOARD https://forum.duolingo.com/comment/17486118 These links will not only show you how to get the Greek keyboard but also how to find the Greek letters on it, how to add accents etc. https://www.duolingo.com/comment/22040507