The only way the white can disappear is if you make it so (or if the file/software is shot I suppose). If the color itself is not set for transparency, check the object for an alpha setting. Then check that the layer it's on is not set to be something other than a regular display layer.
I feel like an idiot, because I have no idea what you just said.
How do I check the 'alpha setting'?
To check for alpha select the object in question, then look at the "COLOR EFFECT" section of the properies. If the pulldown menu there says "Alpha" or "Advanced" you want to check out the values below.