KEV,
Keeping Jelly's in the home aquarium is (would be) difficult to say the least but it is possible provided you are dedicated and have some realatively deep pockets
You should start by reading everything you can get your hands on and even that will probably not be enough. Research, research, research and then perhaps reconsider
As for requirments though try to find Aurelia Jellyfish as there has been some success with raising them. You will need a special tank to house them called a Kreisel (more research) essentially it is similar to a clothes dryer. Water (instead of heat) is gently circulated and removed. Since most Jelly's do not swim, but float, constant motion has to be maintained to keep them suspended in the water. A dead spot or corner in a tank can be fatal. Also the water should be kept between 55 and 65 deg for the Aurelia species. Once you get a suitable enviorment remember they need food...live plankton....mutiple time per day. The only lighting you will need is for viewing and water quailty must stay excellent.
IMO not for the avarage hobbyist (not that you are)
HTH
SiF