Yeah, as ralph.m mentioned the images should be at: sites/default/files/imagecache/carousel/
They should be as follows:
- /sites/default/files/imagecache/carousel/Greenbelt workshop.jpg
- /sites/default/files/imagecache/carousel/O4G Winter Small.jpg
- /sites/default/files/imagecache/carousel/Terry Dunnell Web.jpg
The last 3 images do work but going froward it might be a little more complicated than just putting the images in that folder because you're using imagecache which has probably been set up to resize and/or crop images on the fly to fit that particular size. Imagecache uploads the original and then saves as many variations of the original as you need in specific folders. There is probably an image "style" called carousel that has a specific width/length that that those are saved to. If you change the style, imagecache will reoptimize the images without needing to be re-uploaded.
I would look at your system settings to make sure that imagecache is set up correctly and saving the images to the proper spot on the file system. It may be that the original images were not saved and may need to be re-uploaded.