Click on the Settings tab, and then on 'Staff'. You will see the green button on the right side of the page "+ Add Staff Member". Once staff is created, you can start adding them to your Crews. When adding a staff member, you can choose whether or not they receive notifications (an email that gets sent to them every time a booking gets confirmed for the crew they are assigned to).
Please note that a staff member can only receive bookings when they have been assigned to a crew that is all set to be booked! Multiple staff members can be assigned to each crew, but a staff member can only be assigned to one crew.