How do you replace headlight lens cover for Volvo 240 1993?

Unless it is broken or cracked it does not need to be replaced. At Walmart and I'm sure automotive stores there is a product ($20) that restores the lens. It comes in a package...includes two grades of sandpaper, a gritty compound and a sealer. It is amazing. Used it on my son's 1992 Subaru and my daughters 1989 Volvo. They are almost new and you can actually see at night now.