Just like this. Some companies have their own rail sidings - some even operate their own little locomotive to shunt in such sidings. The railway concern operating the main line, branch line or whatever will deliver the wagon of goods to the handover point, which is called the "Wagenübergabestelle", or "Wüst" for short in German, from where the customer will arrange for its placing for unloading. This is subject to the arrangements between the railway operator and the siding owner - sometimes the siding owner will pay for the wagon to be placed for unloading.