When you have inventory, it must be stored somewhere. This is where warehouses and bin locators come into play.
A warehouse is where an organization can store inventory and a bin locator is where that inventory is stored in that warehouse.
To edit your warehouses, select the option "Warehouses." It can be found in options tree at Stock Management-> Warehouses.
After bringing it up, you can add different warehouses to your various organizations. Each warehouse must have at least one bin locator. After that is configured, you can start to place inventory into them.