To add new users go to users > add new in the admin area. When adding a user it’ll ask for the user’s role.
Here’s a list of what each user role can do:
Administrator – Has full access and can add/manage all users.
Editor – Can publish and manage content including the content of other users.
Author – Can publish and manage their own content.
Contributor – Can write and manage their own content but cannot publish.
Subscriber – Can only manage their profile.