It depends what you mean by photo edition :)
If you need comprehensive software you can choose either Photoshop (best, efficient, a lot of features, but paid), GIMP or Paint.Net (free, but more difficult to navigate and less intuitive and not that effective).
If you need just something to apply filters (Instagram-like stuff), you can use Perfect Effects Free or XNRetro. They have a couple of filters and effects to make your photos look more interesting.