How and where do I report copyright infringement? I have found my own images being used without permission?

You'll probably find it difficult to win the case, especially because you're dealing with companies in other countries. This is a problem of the Internet and the law still needs to catch up with this. To be safe do as I do: never put high-resolution images on the Internet unless you don't mind your image being used without your permission. Or watermark them so that it's obvious the image is being used without permission.