In the material colour setup click on the 'tab' tab. Click the square grey box under 'color texture' and the texture window will open. Now click on texture on the top menu and pick add. Browse to your JPG and ok. A thumbnail of your picture will now appear in the texture box. Pick the new texture and it will appear in the map box below. If you choose apply now, your picture should be on the component.
If you don't want a rectangular image on the surface, you can upload an alpha channel picture as well as the image. The alpha channel picture is the same size as the picture file, but has a white area for the sections of the image you want transferred and a black area for parts of the image you want to cut away from rectangular image.
I haven't done this in quite a while, so I won't even try remembering detailed instructions.
