Why does my downloaded image have a white board on art board

John,

You may be able to download the image in a format that supports transparency, such as PNG24, and be happier.

Does is it a .jpg file? 

The jpeg format does not have transparency, thus, your objects on a transparent backround, when saved as .jpg, will display a white background when open in Illustrator, or in Photoshop.

Like Mylenium said it tricky to know what you mean without a screenshot.

I may be that your pixel file has alot of negative (white) space around. Meaning the actual image is alot smaller than the files dimension. 

In which case you could crop out the white space in Photoshop before opening it in Illustrator for example.

I hope this helps,

Sim

It's unclear what you actually mean. Since you appear to be new to this, before confusing everyone further with vague descriptions and inefficient terminology it might be the best thing to post a screenshot.

Mylenium