If you want to do this in AI you would need to remove mask (alt+ctrl+7) and then proceed to subtract your internal shapes from the outside and because of the way you have constructed spocked oval this is slightly tricky but still do-able. Once you have done that I would save it as a Gif to get your needed trans. but the only thing else I would say is that you would get slight white fringing due to the back ground colour. If this drawing was for print this would not be a problem but if it was for the web and the background was not white this would be a problem. The way to get round this would be to use the same colour as a background that you want in the web as this would give the same colour fringing therefore you would not see it.