Are they just scar "markings" or are the indentions in the surface layer? For indention-like scarring, professional products that aid in speeding up "cell renewal" can be a tremendous help over time. I carry one in the line I sell called "AKTA Cell Rejuvenator," but unfortunately, you can only aquire this through a licensed merchandiser. These types of products are usually available in serums and you can find many different brands and kinds at Beauty Brands or Ulta. If you are looking to get rid of the dark scarring a blemish has left behind, something you can pick up at a local drugstore or healthstore is Hydroquinone, the only FDA ingredient approved as a skin bleaching agent. You must be careful with this product, bc like it says, it does bleach the area applied.
A more advanced approach would be to go to a local spa and have chemical peels or alpha hydroxy treatments that would help decrease the appearance of scars. Good luck to you!