1. Create a Staff member (Contacts -> Staff -> +)
2. From the Staff Listing page, click on that Staff member's name.
3. From the Staff member Details page, select the Create User icon from the Options Bar.
4. Add User Information, including Role. Review the different security roles by clicking into the Role field, and pressing the down arrow repeatedly.
5. Create User.
6. From the options bar, select the Envelope icon to invite this user into your account.