I don’t use carbide create, but I do not believe it can take an image. You need to convert the image into a vector. Here is a tutorial on how to do it in Inkscape., which is a free program.
What you want to is find the highest resolution of the image you can. Use google image search and filter by size and try for at least 1024x768 resolution.
Good luck.
EDIT: Should have known Will would have already answered this
