On the Customer, scroll down to Locations and select Create Location. You can also go directly to Locations on the left side bar, and click Create Location from here. This is however normally done at the same time as you create an order.
Fill in the address, name, type and related agreement for the Location.
As a location name, you can provide either the address name or any name that fits the locations (for example Spirii Headquarters). Note that this name will be displayed towards end-users in the Spirii Go app.