read files in asp.net using c sharp

Question

hi , i want to take files (e.g in Notepad) from differents students and store them on the server and check if one student has made a copy and paste of someone else file(in Notepad) with the rest of other files submitted by other students. if the yes return a message to the student who is uploading that file that it has been uploaded by another one .thanks you so much for your help