We have downloaded a font and we have made it into the .fnt and .dds file but the batch file crashes when we open it so how could I work with the font to make it work?
Fonts are useful for messages in game. A logo has nothing to do with the font used by the fullconversion - the logo is simply an image.
Some fonts will not work. Try a few, until you find one which doesn't crash the game. Then go into your image editor of choice and create a logo using that font.