i am just a hobbyist, and got contacted by Getty images.
GETTY guys do look into all the photos you upload in flickr.com... if they see something they like, they will ask you to become one of their contributors.
then pag may nabenta sila, they'll send you a check
so create your flickr account and start loading those photos... kahit na kuha lang sa compact cam, pwede rin nila ibenta, as long as it's interesting...