I tried all the keys but could not find the first letter for this work in Greek
HOW TO GET THE GREEK KEYBOARD 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 It will also help you learn the alphabet and where to find other
THE GREEK ALPHABET https://www.duolingo.com/comment/22424028
And here is another to help you navigate Duolingo
FAQ - General Questions, Bugs & Reports https://www.duolingo.com/comment/23799672
Some simple hints to get you started:
1.Always read the comments before posting.
Read the Tips & notes right below the list of lessons on your Homepage
Read the drop down hints. Pass your cursor over a word and a list of words will appear.
These are the official Duolingo guidelines which you should read. https://www.duolingo.com/guidelines And these will answer lots of questions about how Duo works. https://www.duolingo.com/comment/8000024
If you have questions just ask.
Hi. I have a question. In the spelling of words, is there a way to know when to use "ο" vs. "ω" and "η" vs. "ι" vs. "υ" since they are pronounced the same way? Or do we just have to memorise cases like this one?
Basically, yes you need to learn the spelling of each word. Of course Greek is much easier than English in that each word is spelled just as it sounds.
One helpful hint is the use of omega "ω" which is always used for the first person singular in the simple present, for example "I play" παίζω, or "I see" βλέπω", "I write". γράφω" etc.