To use these sunglasses, simply place them on your toddler girl's face. The removable neoprene strap can be attached if you want to prevent the sunglasses from falling off. When it comes to maintenance, use a soft cloth to gently wipe the lenses clean. Avoid using harsh chemicals as they may damage the sunglasses. Also, store the sunglasses in a cool and dry place when not in use. Make sure to check the strap regularly for any signs of wear and tear. If the strap gets dirty, you can remove it and wash it with mild soap and water.