fixmycrashes

I extracted the file, opened it in GIMP, made the changes I wanted, and saved it as a .DDS file in the fallout4\data\textures folder. When I launch the game it's still using the vanilla textures. I feel like I'm missing a step that tells the game to use the new custom file instead of the default one or something. Couldn't find an answer through google. I've downloaded a couple texture files that other people have made and they work fine so I can't figure out why mine won't. Never done anything like this before. Help?