There's two methods listed. Which one did you use? What DID happen when you tried it? "It didn't work" is not descriptive. We need to know what DID happen when you made the attempt.
Beyond that, make sure to post the file that you created or changed. The .properties or .json file that the post mentions. Upload the actual file, not just a screenshot of it. Any file host will do. You should also post the exact path that you created to that file, relative to /assets/.
You need to give us actual information to work with in order to help you. So please, help us to help you!