To add a mailing address, navigate to Manager Home > Customer.
Search for the customer you wish to edit > Click on the customer's name > Click on Cust Details.
At the top of the customer profile, click on the "Mailing Address" button.
A window will appear where you can enter in the mailing address and save. Once you have saved, the address will not appear on the customer profile itself however you can click on the mailing address button at any time to view or edit the address.
Be sure to save your changes.