Every course has a gradebook within it. This is where all of the grades go for each gradeable piece of work. Things that can have grades include: assignments, quizzes and discussions. In order to get a grade it is not always necessary that a file should be submitted as this would be impractical for something like a presentation. The gradebook is really just a table that where the grades can go.
Currently the gradebook is NOT connected to the student records system, so the grades you find in learn.gold may be subject to alteration, so please always check with your department.