All Wikimedia projects have rules. Here are ours.
Listed here are the official policies of the project, you may be referred to some of them if your early attempts at writing articles don't follow them. Don't let this discourage you, we all had to start somewhere.
The rules and guides laid out here are intended to keep content to high standards and meet certain rules the Wikimedia Foundation applies to all projects. It may seem like a lot to read, but you do not have to go through it all in one sitting, or know them all before you can start contributing.
Remember, you should enjoy contributing to the project. If you're really stuck come chat with the regulars. There's usually someone in chat who will be happy to help, but they may not respond instantly.