The best way to get started with DiffPlug is to dig in! Once you have installed DiffPlug, you can follow the quickstart to get yourself oriented. Once you've done that, you'll have the background to learn about whichever kind of file or file system you want to work with.
If you've used DiffPlug 1.x before, you'll save yourself a lot of confusion if you start with migrating from 1.x to 2.x.