Help a newbie develop this

[megapan]

It's like a test paper submission system wherein each student will have an account of his own logging into which he'll be shown the test papers he's still to write for the different subjects he has as part of his course and the grades he's been given on the ones he already has. Each of the different subjects of the course will have an account of its own. The professors can log into account of the subject(s) he's responsible for and will be shown the papers he has left to correct along with the student IDs/names (clicking on which he should be shown the answer paper with a field for entering the grade) , the IDs/names of students who have yet to submit the papers (he should be able to send a reminder to those in this category) and also the IDs/names of students whose papers have already been corrected along with their grades.
I know a bit about frontend development so it's the backend where I need help at. So please tell me atleast where to start :(