If your teacher told you that then (s)he obviously thinks you should be able to do it.
If you get stuck on a particular point then people here will help you.
Just saying "I need help" will get you nowhere.
I think your teacher said that way for you to understand but the thing is that's no correct because notepad is a program.
Take it this way: Build a java desktop application that lets you save to file (in txt format) the content of one input field. The GUI will have a button to save to file and each time this button gets clicked a new file will be created with the content of the input field, as initially, after this action the input field will be cleared.