Duolingo appears to be anit-contractions (or maybe just the Finnish one), so you have to rephrase all of your translations to remove any contractions even if they end up sounding rather unnatural. (To be fair, contractions are difficult for foreiners learning English, and there are several dialects of English outside of America that don't even use them.)
Duolingo should be consistent in its translations. If "täällä" was introduced as "over here", it shouldn't suddenly pop up as "here" as the main translation. I thought the proper way of saying "here" was "siinä". Even though they're almost identical, distinguishing them first only to mix them later on is not a good teaching method.