Access iPhoto photos?
You can reveal a particular photo by control-clicking it within iPhoto, and selecting the "Show File" menu item in the contextual menu that pops up. That will reveal the actual image file for that photo in the Finder. I highly recommend not moving that file anywhere, since that will cause iPhoto to lose track of it, but you can copy it to another folder, attach to an e-mail, upload to a website, etc.