Many of us have lovely amaryllises blooming in our houses over the holidays, either by design or from gifts.
If you are not sure what to do, pot it up in regular potting soil, hopefully with some crocking or stones at the bottom of the pot. Water it well, put it in a place with good light, not direct, and wait. When you see signs of growth, water it SPARINGLY once a week. As the shoot with blooms gets taller, give it a bit more water. Once it is in full bloom, water it at least once a week, or when the soil feels dry to the touch.
And then what?!
After it has finished blooming (cut off the spent blossoms and then the stalk as each fades), put it in a place that receives good light, but not sun. Water it occasionally, maybe once a month, until spring. It will go dormant. Cut off all yellowed foliage. After danger of frost in the spring, place it outside and out on a sunny wall, or some other place. Give it a good fertilizing in the spring, and probably one more time over the summer.
As fall approaches, let it die back — no more water — and bring it inside to dry off. Ideally you will unpot it, continue to dry it off, and before Christmas repot it. But I am not an ideal woman. I just start watering again.
And it will sprout and bloom again.
The secret is in lots of sunshine over the summer, good fertilizer, and luck!