rhonda, how much experience do you have with marine aquariums? I wanted to turn my 20 into a reef, and I did almost all of my research on it here.
Probably the best help I can offer is to tell you to READ READ READ!
Go through the saltwater threads, especially "getting started" because people ask this question almost on a daily basis, or at the least weekly. Find out what you like, find out what you need, etc.
I'd also reccommend the book "The New Marine Aquarium" by Michael Paletta. It's a great book for folks who are starting out in marine aquatics.