Where and how can I fix my Iphone5 screen?

Recently my Iphone 5 got a slight crack on the screen, its barely noticeable, but I still would prefer not to have any cracks or damage to it, can anyone tell me how to get it fixed? Its not big in any way, just a small knick on the screen, can anyone help and tell me where to go to fix it?

Apple $199 to fix

Polishing it with an electric polisher is the best way. But it won't be easy.