Welcome to R2R! This is a wonderful place to get started. I agree with this ^^^. Decide what kind of fish you want to keep, then decide if you want to keep corals as well. Then you need to set yourself a budget, then add about 50% more to it lol. This is an expensive hobby but it can be done on a budget.... i do. Research everything... Every animal you want to keep, every piece of equipment you want to use. Ask tons of questions.
Read this.... a very good place to get a baseline understanding http://reef2reef.com/threads/the-supreme-guide-to-setting-up-a-saltwater-reef-aquarium.138750/