To use your new cotton flannel sheet set, simply put the flat sheet on top of your mattress, the fitted sheet over it, and place the pillowcases on your pillows. For easy maintenance, you can machine wash the sheets in cold water on a gentle cycle. Make sure to wash them separately to prevent damage. Avoid using bleach as it can harm the fabric. When drying, use a low - heat tumble dry setting and remove the sheets promptly to avoid wrinkles. Do not iron the sheets. If your home washer or dryer doesn't have enough space, you can use a large - capacity commercial washer or dryer. With proper care, your sheet set will keep you warm and comfortable for many winter nights to come.