How can I sell my photographs and give the money to charity?

I love photographing flora and fona especially birds. I would like to post my pictures online so people can buy copies. I would then send the profits to an orphanage in El Salvador than I lived in for several months. The money would go for helping pay for the kids schooling. Is this as simple as posting pictures on flickr asking a certain price and then sending the money I recieve. Should I mention I'm doing it for an orphanage? should they write the checks to me and then I write it to the company and send the profits to the orphanage or what? Please help!!!!!!!!!!!!!!