You should not need to do anything to support Photon; it works "out of the box" with all the images on your site.
If you experience issues on your site, it might be worth checking our documentation first:
http://jetpack.me/support/photon/
If that doesn't help, do not hesitate to post again here with some details about your site and the issues you are having; we'll be happy to take a closer look!
Thanks!