Step #1: Choose your consulate
You may usually apply at the consulate with jurisdiction over your permanent or your school address. Use this list to help you decide: https://www.middlebury.edu/schools-abroad/schools/spain/student-visa
Step #2: Make a plan to apply and secure an appointment
German Embassy in DC
German Consulate in Atlanta
German Consulate in Boston
German Consulate in Chicago
German Consulate in Houston
German Consulate in Los Angeles
German Consulate in Miami
German Consulate in New York
German Consulate in San Francisco
You need a long stay (over 90 days) national visa for the purpose of study. Schedule an appointment (now) at your consulate here, for a date not more than 90 days before the start of the program.
Step #3: Gather your materials
Consult the requirements here, noting especially the financial guarantee necessary. Students need to show they have enough living expenses for their stay (just over $1,000/month). To do this, you either need proof of scholarship or financial aid in the form of a signed letter stating the amount you will receive for your living expenses in Germany from X-Y dates on institutional letterhead OR you need to open a blocked bank account with the required funds—students have used this one in the past.
Your CV refers to your resume; your certificates of academic qualifications refers to your college transcript. Your letter of motivation can be a version of the one you used when applying to study abroad.