You take an EMT class. If you pass, you're permitted to take a practical exam and written exam, which is given by either your state (in some cases) or a "national" exam given through a testing center.
It's impossible for us to tell you if you can take a 6:00pm class for your EMT, or a summer course, since we've no idea where you live. My class ran one semester, and was from 6:00pm-10:00pm twice a week, and 3 long Saturday classes. You can ask around at any community college nearby, or perhaps even at your university or college. It's generally around $400-900.