Need help with my heavy Metal....

Hello guys,
ah I just don't get it how I can get Metal looking parts on an aircraft.
Maybe some of you noticed my preview pics in the Freeware-Screenshot of my B787-8 - Dreamliner colors.
I saw on the actual Boeing image, that the wing leading edges are made of a shiny metal.
I tried to get the parts look like metal by editing the Alpha-Channels, but when I edited the Alpha-Channels, all I got was, that the parts changed into transparent. I'm using the GIMP for my edits and DXTbmp.
I hope that hasn't been asked yet,
Greetings,
Fabian
ah I just don't get it how I can get Metal looking parts on an aircraft.

Maybe some of you noticed my preview pics in the Freeware-Screenshot of my B787-8 - Dreamliner colors.
I saw on the actual Boeing image, that the wing leading edges are made of a shiny metal.
I tried to get the parts look like metal by editing the Alpha-Channels, but when I edited the Alpha-Channels, all I got was, that the parts changed into transparent. I'm using the GIMP for my edits and DXTbmp.
I hope that hasn't been asked yet,
Greetings,
Fabian