The Death of Superman runs through Superman The Man of Steel #18-19, Justice League America #69, Superman #74-75, Adventures of Superman #497, and Action Comics #684.
They are all on Comixolgy. This is the Death of Superman proper. The issues that Comixology are counting as the first arts of the Death tale are really not part of the main tale. They each contain a single page with (the then unknown) Doomsday pounding against the walls of his underground prison and eventually freeing himself. Asdie from that, the stories are completely unrelated to the Death storyline.
Unfortunately the Death is the only part of the storyline that's up on Comixology. None of the Funeral for a Friend, Reign of the Supermen, Return of Superman stuff is up there.