You can submit new portals (I have done so), but that takes time to get reviewed (4 to 6 weeks according to the FAQ). To kickstart the game, they obviously just

You can submit new portals (I have done so), but that takes time to get reviewed (4 to 6 weeks according to the FAQ). To kickstart the game, they obviously just used pictures scraped off flickr or something - how else could they get a good coverage of the whole world (or at least the major cities), which requires at least tens of thousands of portals.