If there is a better suited forum/newsgroup for MS paint: please advise!

I am trying to generate a few icons using MS-Paint. The icons' background should be "transparent", i.e. not cover the underlying content. What color *is* "transparent"? And can one use MS Paint to fill an images background with that color?

All icons I created so far, have a white background (or whatever I choose as the image's background color) but not transparent.

Michael