A Wikipedian is a person who helps to contribute to Wikipedia. Wikipedians are people who join the Wikipedia community. They change pages to add information and improve them. Many of them register an account, so they can do more.
Anybody can change Wikipedia - you can too. Click the Change or Edit tab at the top of any page to change it.
Wikipedians can edit pages anonymously, or with a user account. Some pages are protected. Wikipedians without an account, or whose accounts are less than four days old, or who have made fewer than ten edits to unprotected pages, cannot edit protected pages. They also cannot move or delete pages.
Some editors with much more experience become administrators. They can block or unblock users, protect or unprotect pages, and edit fully protected pages, such as the Main Page.