Fuzzy Overlay on mask?

I have a very reflective mask for my character, and I want to put a texture that kinda looks like its dirty, but I don’t want it to cover up the rest of the mask, I tried using an alpha mask, but it gets rid of the whole mask look and not just an overlay look, how can you get rid of the alpha on one texture? That is what I would like to know, is it possible?

bump, please help, all i need to know is how to use alpha on only one texture?