Choose your foreign language of choice and take the entry level class. If you enjoy the language, speak with your professor about meeting with an adviser in the department. An adviser can help you plan your college career path in the foreign language. The adviser will tell you what classes you need to take, how many internship credits you need and other qualifications.
Declare your foreign language major with the college. The process will vary from school to school, but generally requires you sign a paper to put on file that you are a foreign language major. At some schools you may need to meet with your bachelor of arts adviser to declare as well.
Complete all the required credits (and classes) as well as work experience. Upon completion you will be able to graduate with a foreign language major.