If you are new to diving the first thing you will want to do is get certified. Not only do you need certification to dive safely, but most responsible dive shops will not rent equipment or fill tanks to people who are not certified divers.
There are several scuba diving organizations, most notably PADI and NAUI (although there are others). Most of your local dive shops offer Open Water classes and certification courses outlined by one of these two organizations. Start by calling your local dive shop and get class information from them.
Once you have your certification in hand you have the option of broadening your diving horizons with Advanced Open Water, Rescue Diver, Master Diver, Cave Diver, Drysuit Certification, Underwater Photography and the list of certifications goes on. It all depends on where you want to take your scuba adventure next.
For the truly adventurous diver there is Technical Diving. Technical Diving involves complex air mixtures, long decompression times, a lot of training and very specialized equipment. The rewards are very deep diving and areas of the deep that are otherwise inaccessible to the rest of the world.
For those who want to make a career of diving there is also the Commercial Diving path. This sort of career involves off shore oil rig repair, salvage, research and other underwater construction and maintenance type jobs. There are several Commercial Diving schools throughout the country and many offer financing. One thing commercial diving guarantees is a very adventurous career where no two days are exactly alike.