@firsal
Welcome to the game, it has more space based 4X awesome then graphics but DF has proved that can be a good thing. Anyway there are tutorials and such around (ask others I mostly bumbled my way through and don't know any good beginner ones) that you can check out though one of the things I would advise is checking out some of the stories out there, it may or may not help you understand the game but in the least they tend to be good reads. Two AARs which are quite decent are on the Paradox forum and done by Blue Emu, you can find
his first here and
his second here. Both are fun reads and the second is done with version 6.21 so since they aren't continuations or anything you might want to start there though they do refer to the previous one somewhat. Also you can check out the
Steve's fiction sub-forum in the Aurora forum to find stories by the game's creator himself. The stories are good though he tends to not finish them (as in wrap it up, hard to finish an Aurora game since there technically isn't any real end) because he has started a new campaign as he uses them for testing. There are undoubtedly other good stories out there and besides my own video LP there seems to be some other Aurora videos on YouTube including normal games and tutorials as well so if visual is your thing you can find those though the best stories tend to be the written kind as it is easier with that.
@others
how small can an EM sensor be and still detect a colony. I have been playing around with fighter survey vessels and I would like to be able to just stick a 0.1HS EM sensor on one if it would detect an NPR colony when surveying the planet. Also if the ship gets pinged by an active sensor would it detect that as well or what. I guess it really comes down to me not really understanding the ranges and such of passive sensors.