MDN Web Docs is a wiki, where anyone can add and edit content. You don’t need to be a programmer or know a lot about technologies. There are plenty of things that need to be done, from simple tasks such as proofreading and correcting typos to the complex ones such as writing API documentation.
Contributing is easy and safe. Even if you make a mistake, it’s easily fixed; if you don’t know exactly how things should look, or your grammar isn’t all that great, don’t worry about it! We have a team of people whose job it is to make sure that MDN’s content is as good as possible. Someone will be along to make sure your work is tidy and well-written. Share what you know and follow your strengths, and trust in the rest of the community to help make your work even better.