Getting an altered dds file to work

[mongoose]

I just used paint.net to change this dds file (made a bmp.first)

to this

Now I know I have to add a layer or something to get it to be like the top one but I forget how! Doesn't seem to work just adding an alpha layer?? A Transparency or something/ I have GIMP which I could use but it doesn't do dds files so have to go to something else first and then convert.

 

[mongoose]

Well the simple answer is to repaint in the dds file using paint.net. Did find a work around using GIMP but far more complicated.