Dermatology is a medical specialization. You will first need to get to any medical school and then do your internship and residency at specialized skin clinics.
Many colleges have dermatology programs however a good way to start with a abse education is through an esthitician school or aesthetic course. The Dermal Institute offers many secondary classes as a way of learning as well.
If you want to be a dermatologist you have to have an undergraduate degree and then go to med school. During Med School you can pick a specialty to study which would be dermatology. New York University has a good dermatology department.
Before you can study dermatology, you must attend medical school, and once you are an intern you may study dermatology. Harvard has a top dermatology program.
Brown University has a program in dermatology that is pretty good based on students who are currently attending the college. There is also Columbia university that offers and excellent program as well.