There are two options where you can add your shipping address. You can enter the address in your Shipcloud webUI as well as in the settings of your plug-in / your integration.
WebUI: You can enter your ship from address as well as your return to address in your account under "Configurations" >> "Shipping Addresses".
Plug-in / integration: If your plug-in or integration enables you to enter a shipping address directly in the backend, Shipcloud uses that address to create labels. If you cannot add your shipping address there, the data of your WebUI will be transferred to the carriers.