Good for you! There are lots of different areas you can be in with mental health. If you would like to be a psychiatrist you will need to attend medical school. Here is some great information on it http://www.psychiatry.com/student.php
You can also presue areas such as being a social worker or mental health therapist which will require a little less school but you will not be able to prescribe medications. If you become licensed in both of those areas which will requrie a masters degree then in most states you can open up your own private practice.
Let me know if I can help anymore or answer anymore questions!