Yes, if you're growing your orchids indoors, it's a great idea to spritz them to keep the humidity up around them. Once you're running the a/c in the house, it gets a little bit dry for them so anything you can do to keep humidity up a bit is helpful.
Their care really depends upon the type of orchid you have. If you've got more questions there's tons of info over at the Orchids forum.
http://garden.org/forums/view/...
