In order to add new user go to Property Management, Staff Management and choose Edit Staff Members.

You will see the Manage Staff Members window where you can Edit, Delete and Add users:

When you click on Add user button you will see another window, Edit User. In the User Details part, enter the e-mail, the first name and the last name of the user. On their right side choose the role for the user.

Save the changes. At this point, the system will send an automatic message with the password to the email of the user so that he can enter his account.

See also: 

Setting up roles

How to reset user's password?

How to change user's password?