okay. i tried this than RetroGRP(because SFGrpConv has less complicated things for a noob like me )

I've open the corsair.grp but what's next? what about the pallete file? is it in the same .mpq files in starcraft directory?

stubbornly, i choose the same corsair.grp and viola! it generate pics of corsair in full black color(w/ blue dots)

i want to know what's this SFGrpConv can do to improve my mod

For units, you have to use the unit palette. I think it comes with SFGRPConv, but I'm not 100% on that. If you can't find it, I'll send it to you later.

This is a little trick, but listen (or read, whatever).
RetroGRP includes the different palletes in its folder (or zip), so you can borrow them for a while...

Or better yet, get this.