how to get a phd

Most programs require somewhere in the neighborhood of 30 hours of departmental coursework, while others require more or less, depending on the field. As with most advanced degrees, youll likely need to pass all your courses with at least a B, or better.
In graduate school, the course load is usually somewhat less than the undergraduate degree, because of the intensity of the coursework and other research or teaching responsibilities. A full load is usually considered 6 or 9 hours, though youll be doing 20 or more hours of teaching or research in a given week.
For a PhD student, a typical coursework semester might involve three courses: a required core class and two elective courses. Typically, elective courses will still be in the department the student is studying, if not the particular program. For example, a comparative lit PhD studying Medieval literature may take a 20th century poetry course in the English department as an elective, though probably not a biology class.