You can easily add users and assign them specific roles in your WordPress site, simply login to the admin panel of your WordPress site then visit Users -> All Users page.
Click the ‘Add User’ button, enter the username, real name, email address, you may select to automatically send the username and password to the newly added member or deselect the checkbox to manually send the username and password to your site member.
Once you have added all-important details of the user, simply click the ‘Add User’ button and the user would be able to login to your website.