I don't suppose you know what kind of orchid it is- cymbidium, phalaenopsis, brassia, dendrobium?
They like humidity- so the most likely reason they are in the bowl on top of rocks and water is becus it helps keep the reas around them humid. Just make sure that the roots are not in direct contact with the water-you don't want the roots to rot. You can also mist the leaves in the morning-but don't mist the blooms or buds. water them thoroughly about every 5 days. Typcially keep them in indirect/filtered light. NO direct sunlight. The root looking things are supposed to be there as that is how the orchids get their water-are they all shrivelly looking and whitish grey/brown, or are they relatively green in most spots?
Sorry for the rambling, i might be able to be more specific if I know what type of orchid it is. you might want to try going to orchids.com and looking at some of the pictures of the kinds of orchids they sell (I swear I'm not promoting for them!
good luck!! orchids are great
plants and not nearly as difficult to care for as some people expect!!!
lilitu