To wear this dress, simply step into it and pull it up over your body. It's a backless design, so you'll want to choose undergarments that work well with that style. When it comes to care, it's best to follow the washing instructions on the label. Usually, a gentle machine wash or hand wash in cold water is a good idea. Avoid using harsh detergents that could damage the fabric. As for the small black mark, try spot - cleaning it gently before washing the whole dress. Store it on a hanger in a cool, dry place to keep its shape.