Did you keep your Poinsettias from last Winter? Now (October) is the time to get them colored up.
They need 14hours of darkness each day in order to bloom. By darkness, I mean complete darkness. Even cracks of light can impede its process. The rest of the time, the plant needs bright light.
The easiest way to do this is to put them in a warm closet where you can regulate the amount of light that it gets. Keep it moist and warm, Poinsettias are tropical plants.
When the Holidays are over, they will start to shed some leaves and go dormant. That means you can plant them outside if it is warm enough, or you can plant them in a bigger container with a lot of love and fertilizer. It’s not an easy process, but it doesn’t take many steps. Generally, after a month of doing this they are starting to bloom but will require a couple more weeks of alternating light to reach their full bloom.