you'll have to download a greek language pack. If you have windows just go to; settings -> time and language -> region and language -> add language, and find greek. hope this helps. :)
You need to have several at different heights. That way you can have a little path running down the middle.
Hello and welcome to the Greek course! Please read instructions on how to get a Greek keyboard on your device here https://forum.duolingo.com/comment/22040507.
Your question has also been answered in this discussion - if you read the rest of the comments you will find jaye's instructions and helpful links. ;)
I added the Greek keyboard and now I can switch back and forth using the space key. Since "nee" is not an English word, my guess was that. they were naming the Greek letter η. Apparently the correct answer is " ηι" which either the Greek word for "neither" or the Greek spelling of the name of the letter η.