Answer:
You sign up at a local dance studio and enroll in lessons on a daily basis.
Take into consideration of what style or styles you want to study though before picking a studio so you can select a study that's strength and/or focus is that style(s).
Start off slow if you never have danced before. But as for everything, practice makes perfect. So, the more classes you attend, the better you will get in a shorter amount of time.
Remember, it is never too late to start. If you are an adult, there are plenty of adult classes for those who want to learn the art of dance or simply get good exercise.