Anyone can edit Wikipedia! Those who take the time to do so are generally smart, curious people who care about a subject and about the encyclopedia project. Wikipedia welcomes new editors: if you are willing to learn a little bit about how the site works, and can improve an article to help make it better, you can help Wikipedia.
There are thousands of Wikipedia editors, and they come from all over the world. Young and old, experts and non-experts, they have different interests but share the same set of goals.
All articles need to comply with the following basic principles:
Anyone can edit: you don't even need to create an account. However, it is a good idea to do so: just go to the "log in/create account" link in the upper right-hand corner.
Once you've done so, click the "edit" link at the top of the editing window. You will see a window that contains the wikitext. Make your changes here, and then hit "save". That's it: you just edited Wikipedia!
Wikipedia uses a simple, intuitive layout to keep the focus on the information, not the design.
The page layout has the following tabs at the top of the window: