While you are logged in, go to the upper left hand Menu. Select Administer - User Management - Users.
Click the tab at the top that says “Add User”
Set a unique Username (typically a first initial, last name), their email address (the system only allows one instance of each email address) and set a password (they can change this later).
Select a role for the new user. If they should be an editor, select basic-editor. Otherwise, leave only the Authenticated User box (default) checked. Authenticated user allows the minimum amount of access and is the most restricted user-type. Authenticated Users will not be able to edit content on your site, but can interact as an outside user anywhere permission has been granted. Only allow higher level permissions to people who should have editing access.
If you would like the user to receive an email notifying them of their new account select the “notify user of new account” box.
Click Create New Account.