For a more comprehensive overview of how Warehouses are connected to everything, see the following link:
Warehouses on Desktop
Set up your Warehouses by going to File -> List Management -> Inventory -> Warehouses
Click 'Add New' to create a Warehouse. Highlight an existing Warehouse and click 'Modify' to edit them.
Warehouses on Portal
Go to More -> List Management -> Inventory -> Warehouses
Click 'Add' to create a new warehouse.
Click the Ellipsis -> Modify to edit an existing warehouse.
Write the name of the warehouse and select which brand it should be in.