- MAJOR spoilers-
you got the bad ending if you threw Namatame into the TV. In that ending the world is still covered in fog. Nanako stays dead and you never catch the real killer. Yu goes back home afterwards.
You got the good ending if you calm everyone down and don't throw namatame into the TV. The game will continue from there and you go on to pursue the real killer. (this includes picking the right killer when prompted, otherwise you get another bad ending if I recall correctly).
for the true ending if you dont go home on the last day or something...Haven't gotten that far yet honestly, I still need to get here. The lovely link the person above posted tells you how to get each ending, with no spoilers at that. Very convienient, I used the same guide.