Images on Blog Page

I was using Yoko theme and my images would show on the single blog page and the “main” blog page that shows several past entries. Since I changed themes to Twenty Ten, the image does not show on the main blog page. Is there any way for the image to show? I usually use a URL (from my domain) when inserting media and do not upload all to the media library.

This is my site. These images that show had to be uploaded into the media library. The photos from the past posts do not show because they never had to be uploaded. This is only with this theme. Is there any way to program this to use the image URL I have uploaded with the post?