This might be a bit late, but:
The application process varies from university to university, but most will only require your high school transcript, maybe AP/SAT results and usually a certificate to fulfill the language requirements. Some universities will also interview you and/or conduct additional tests.
Since I’m from Germany, I don’t know what the process looks like when applying from the US. However, if you have questions regarding the application process, it might help to contact the international office of the institutions you’re interested in.