The reality is that no one knows how to do any professional job when they graduate from college. What we learn in college is mostly how to learn and how to problem solve. The problems we solve in college, whether stumbling through our first sorting algorithms or writing a paper about the role of Prussian nationalism in the 1800s, are not tied at all to the problems we have to solve professionally. And that's okay. When it comes to being a practitioner, whether producing commercial software products or writing analyst reports on public companies, the job itself is the best training. What you have to bring to the table is the curiousity and ability to learn and problem solve that get you up the learning curve quickly, and the professionalism that makes you a reliable and welcome colleague.