In order to add or edit office locations, you need to navigate to the "Offices" tab within the company module.
As an admin you will be able to add multiple office locations or update your primary office location. By clicking the office location you will be able to edit the address and view all employees that are assigned to this work location.
If you need to update or assign an employee's office location, you can do so by going to People > Employee > Job & Pay > Employment Information.
Please note that in order to add an employee to payroll they will need to be assigned to the primary office location, as the primary address will be used to determine the jurisdiction where the payroll is taxed in.