How to use selenium web driver for testing forms that requires user to be already signed in?

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How to use selenium web driver for testing forms that requires user to be already signed in?
for example, i have a student management system which contains both MS and BS Students.
System provides functionality of "Registering Courses" which requires user to be logged in and this page content would depend on whether the student is from BS or MS.

If i directly open that registration page it would show an error and ask for login. Is there a way, e.g. cookies, to keep state of system? I'm using Junit for testing.