I've been playing with just leaving one out in the garden. So far it puts out greenery each summer but doesn't loose it at the right time so I suspect I am not getting dry enough conditions in the garden which is what Amaryllis need to signal it to go into the dormant and then flowering phases. Of course my climate is probably not quite right for it either, so it isn't a serious effort. LOL I haven't bothered forcing one indoors from an existing bulb but the people I know that have done so tell me it can be done and it isn't super hard. Famous last words,
but you should still give it a try if you like the ones you got.
Let the ones you force go through the complete cycle of getting leaves and wait until it stays warm in late spring to take them outside. The leaves will be putting energy back into the bulb for next year's flower. It will stay growing and green as long as it gets regular watering and feeding. Then you can either induce dormancy by stopping watering entirely or waiting until cold weather damages the leaves a little.
The tricky part is timing. Not only do you have to make it go into dormancy, you have to time that dormancy to around 12 or so weeks before you want to force the bloom to appear. Once it is dormant you have to wait close to 3 months before you want begin to water and feed it again. So far I have only seen this done successfully with Amaryllis kept in pots, not ones fully planted in the ground, although you should be able to dig one up and re-pot it just as easily. If put yours out of doors and don't mind a later bloom you can try waiting for them to loose their foliage after the first freeze/frost in the fall (it won't be blooming again until late winter). Cut off the browned and dying leaves and put the bulb in dry and cool place, leaving it in dry soil in a snug fitting pot (it is one of the few plants that likes crowding). Basements are perfect for this dormant state since the recommended temperature is around 55 degrees F. Give it about 10 weeks of "rest" then begin to water it and place it near a window where it gets sunlight and stays warm. This last part is just like the directions you should have gotten with the ones you purchased.
I hope you post up some pictures of the pretty flowers that you should be getting in a couple of months!