Wikipedia is a global collaborative encyclopedia written by people from all over the world.
It can be a bit complicated jumping into such a big project, and you may feel a little overwhelmed by the sheer size of everything... but these guides will give you a good idea of how to make your first few edits. If you want to make test edits, you can make them here, and if you need help along the way, you can chat with a Wikipedia volunteer online.
Editing most Wikipedia pages is easy. Simply click on the "edit" button anywhere on a Wikipedia page. This will bring you to a new page with a text box containing the text of the current page. In this box, you can change the text, fix spelling mistakes, and eventually do more advanced things like inserting images, or building tables. Don't worry about indenting paragraphs or doing complicated HTML.
When you have finished making the edits in the text box, you should write a short edit summary in the small field below the edit-box, describing what you've done. To see how the page looks with your changes, press the "Show preview" button. To see the differences between the page with your edits and the previous version of the page, press the "Show changes" button. If you're satisfied with what you see, be bold and press the "Save page" button. Your changes will immediately be visible to all Wikipedia users. Click here to find out where you can help!