Help:Introduction to Wikipedia - Wikipedia
How you can contribute
Don't be afraid to edit – Anyone can edit almost every page; just find something that can be improved and make it better! You can add content (using references to support your claims), upload free-to-use images, correct spelling and grammar mistakes, improve prose to make it more readable, or any number of other tasks. It's normal for new contributors to feel a little overwhelmed by all of our policies, but don't worry if you don't understand everything at first; it's fine to use common sense as you edit, and if you accidentally mess something up, another editor can always fix or improve it later. So go ahead, edit an article and help make Wikipedia the world's best information source!
Donate – Wikipedia is free to use and edited entirely by volunteers, but it relies on donations to keep the servers running. Please consider donating to help fund the project's maintenance and development costs.
Sign up for an account
You're welcome to edit anonymously, but there are many benefits of registering an account. It's quick and free.
Why not try out the editor right now?
You can test out how editing feels by editing one of the "sandbox" test pages below:
Just type some text and click Publish page when you're happy with the way it looks. Don't worry about breaking anything; these pages are open areas for experimentation.
There's plenty more behind the scenes
Wikipedia has many community pages in addition to its articles.