Regression Testing Eclipse

I am working on a programming assignment in Eclipse. The assignment requires an input file of "personality.txt". I dragged personality.txt to the root folder. To be honest, building paths, source folders, packages, and other components of Eclipse still confuse me as well. I know how to use them, but I don't fully understand the underlying concepts. Can anyone recommend good reading on these topics?

Now to the real question. Sorry.

It is not an assignment that requires many classes or higher constructions. I simply have a main method that runs everything and a variety of other methods that accomplish various tasks.

So far, I have been testing simply by running the program and inputting (as user input) "personality.txt". My question is, what is the best practice for testing something like this in Eclipse?

Thank you all in advance!