Reef Central is your friend. Read lots and ask questions.
Also look for a local salt water aquarium club. There is nothing like having people local to you that you can talk to. Reef Central used to have an index of clubs throughout the US.
Salt water is chemically more complex than fresh water and more care must be taken to maintain water quality.
Corals cover a wide range from fairly hardy to very demanding of high light and current conditions to remain healthy.
Careful of advice from stores. Many are more interested in selling you lots of 'stuff' than in keeping things alive long term.
If you decide to go ahead and want more detailed info, let me know.
