Hiya, wondering why there is not so much explanation of Polish Grammar past the first section? It gets into plurals and more difficult parts of the language but doesn't explain any of the rules anymore :(
They just haven't written the tips and notes for all of Polish yet. Hopefully they will soon, because it's the same way in Ukrainian, and gets really annoying. I don't know any good grammar websites for Polish. If your library supports it, Mango Languages is a good website to go with Duolingo. It explains grammar and helps you speak the language very well.