Light & Water
Peace Lilies prefer medium, indirect light. They can tolerate low light, but may not bloom. Keep them out of direct sun. They are famous for dramatically drooping when they need water, so they'll tell you when they're thirsty! Water thoroughly and let the top inch of soil dry out before watering again.
Flowering
The "flowers" are actually a white, modified leaf called a spathe. To encourage blooming, make sure the plant is getting enough bright, indirect light.