Poinsettias come in lots of colors and sizes, but all love to be kept in indirect light and very moist. Place inside, in front of a window and away from heaters and vents, or on the porch away from direct light.
A good way to keep watered by placing a few ice cubes on the soil every day. Only water the soil, not the foliage.
If the plant is wrapped in foil, remember to poke a few holes in the bottom and place in a saucer for drainage. Expect to see a few brown, ugly leaves – just remove when you water.