On the alpha channel, 0% is white (fully visible), 100% is black (fully transparent). Photoshop will save seperate brush colors for when you have that channel selected. So you'd copy a DDS file (not the alpha layer, the whole file, and rename it to what you'll want), paste your graphics over the graphics then black out the alpha channel and use white (and shades of gray for medium amounts of transparency, 50% is medium gray and is 50% transparent) to "color in" the parts of the image you want to show.
Quib
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