Problem with making flagdecals

[BORNAparte]

I'm working on Czech nation for CivIV and it is practically completed. I can't do flagdecal in DDS Convertor only. That flag is white in the game (I think it is because alpha channel). I don't have Photoshop or something similar. Can somebody help me? This is that flag:

If you can convert it to .dds what will be function please do it. Help me please!

Edited:
It is done now. The czech flag is completed. Czech nation will be added in several days. I thank everybody who wanted help me.