If it is a question, use a question mark. Also try google translate, it gets it right pretty often. I've checked it for this sentence and it is absolutely right. Still,
ten pomIdor jest dObry.
Capital letters denote where you should stress. "ten" and "jest" have only one syllable, so ...
tldr; use question marks and google translate.
I'm on Android too. You don't see the English translation on this linked page?
Cases also come into play! For example, Nominative case is the base form of the word "the woman / kobieta". But in Instrumental case, (to be/this is kind of thing) "Ona jest kobietą / She is a woman". If you go on the website, there's a button called Tips and Notes that you can press when selecting a lesson! You'll learn a lot of things that aren't explained in the app there!