Get inside the epub
First, you need to get at the code inside the epub. An epub file is just a zip file (a compressed folder) with the file extension changed from .zip to .epub. So:
- Change the file extension of the .epub file to .zip.
- Then extract the contents as you would any zip file.
- You should see a file called mimetype, and two folders, META-INF and OEBPS. (Sometimes you won’t have OEBPS, but just the files that would normally be in an OEBPS folder. Sometimes OEBPS is called something else, like “content”. That’s all fine. Leave it this way.)
Next, you’re going to make a bunch of changes to the files you’ve extracted, and then zip them up again.