Since with that subject matter odds are you would be teaching higher level students, your current age and above to university level, you would definitely need a Master’s degree and possibly a Doctorate. In any case, your university should be able to give you the list of classes you need to take in order to get each of the degrees.
Generally, as others have said, you will need to fulfill your requirements in General Studies, including math, language, literature and bits of science, history and art. Then you would need to take the courses for your major. Most university counselors can provide you with a list of the required courses and the recommended courses.
In addition, you might look around to see if your schedule and course plan will allow you to take a few classes in the philosophy of teaching, or teaching methods.
Are you planning to stay in Hong Kong for university or try a different country?