you need to create an instance of PersonalInfo in your EmplInfoc you do that by using the
new
keyword. E.g.
PersonalInfo personalInfo = new PersonalInfo();
personalInfo.APublicMethod();
This is very basic however, so I don't feel you will get satisfying answers here as explaining the basics takes a bit more then a few lines of explanation. I suggest you go to a bookstore and find yourself a book.