Do you currently work in the dental field? I would say the best way is to learn web design yourself, start your own web design service, build up a portfolio. You can do that while working a day job in another field. Then judging by your portfolio and your success that way you could possibly look at further studies, working for a professional design company etc. In my opinion, you have to have talent in that field, whilst you can study and learn, it is a field that you need to have a natural talent and flair for.