There are a variety of forms you need to complete that you can pick up at the Admissions and Records office. You will need to secure permission from your parents and be recommended by your high school principal.
Credits earned will be applied toward college credit and may also be applied toward high school credit. You will need to speak with your high school personnel to determine if these courses will count toward high school credit, too.
Since these are college-level courses, you should be in excellent academic standing at the high school. Again, you must be recommended by your principal and he/she can determine if you are academically strong enough to succeed in college courses.