Do you mean you don't know how use the mod?
Well in that case, here's a short answer.
You take the mod and move it to
LOCAL DISK [C] / Nexon / Combat Arms / Game
Make sure you save the original file by finding it!
[It should be the same name as the MOD file]
It might take time, but it's worth it. Just in case you ended up getting bored with the mod.