Help with textures

Hi, I have some questions about textures. First, I have this object with a texture acting as a bullet hole decal. The problem, is that the center of the texture is black (the part I want to show) and the edge is white. Now, I want to make that white part transparent, not the black part. How do I do this? :?

Any one? Because I notice in HL2, that the bullet hole is just a standard object, with certain parts transparent, to vary based on the object it hit. So how would I make it so lighter parts are tranparent and not darker parts?

Just keep that you want transparant as transparant in photoshop and save it as a png. file. And use nature or something on the shader and you’ll get what you want.

So just make the white transparant.