Correct planting depth and fertilization adjusted to the growing season are good preparation for the cold season. In addition, roses should not be cut from mid-September to avoid new shoots before winter.
Before the first heavy frosts come at the end of November, you should at least protect your more sensitive roses well from the cold. You can find winter hardiness information in the individual rose portraits.
Choose a sheltered location for the rose tubs. Cover the tub with fleece, jute, bubble wrap or coconut matting and place it on footers. Keep the drainage holes clear so that excess irrigation water can run off. 
Before piling your roses in the tub, cut off dead flowers and remove diseased and dead plant parts, which are otherwise a fertile ground for fungi, bacteria or rot.
Piling in the tub about 20 cm high with soil or a mixture of topsoil and compost protects the grafting point (branch base). Covering with container hoods, fir or conifer brushwood or breathable gardener's fleece protects roses from cold wind, drying out and too much sunlight on mild days.
You can get a cozy winter look by using, for example, colored fleece with jute ribbons and using wooden stars or colorful ribbons for decoration.
You can water pot roses occasionally even in winter, especially after a period of frost, frost can dry out the planting soil.