The best way is to buy a new top case assembly including the keyboard. I have done so too and the repair isn't too bad. If you don't want to go through apples self repair program you can search other sites for the right part, just be sure you go with a trustworthy seller.
An alternative, although harder, would be to just but only the keyboard and attempt to peel off the backlight and replace the keyboard underneath. This however is tedious work and will not be fun.