Without explanations, it is hard to know which ending to use when translating to Ukrainian
Yeah. I think, you need more listen to and read Ukrainian to understand why we, Ukrainian-speakers, are thinking and speaking like that, why we use the cases of words (the different endings of the words). English uses specific the order of words to show link, dependence between words, but Ukrainian uses the cases instead of it. So, Ukrainian don't need such rigid the order of words like English.
Here's another website just to help: http://www.ukrainianlanguage.org.uk/read/unit01/page1-1.htm