The plant poinsettia doesn't require watering all that often so they're easy to take care of.
You should water your poinsettia plant about once or twice per week and you'll know when the poinsettia plant needs watered by the weight of the pot that the poinsettia plant is in.
When the pot that the poinsettia is planted in becomes lighter in weight then it's time to water it again which is around once per week.
Also keep the poinsettia plant away from things such as drafts and heat vents and keep the poinsettia plant in a well lit area or where it can get plenty of sunshine.