Scroll down to the Manage Attachment button and click on it. When the box comes up it asks for a url but also has a choice to browse your computer. Use the browse to find your photo and click on it. It will show up in the box. Now click the upload button. When all is done, close the box and click on "Submit post" (or thread)
PS Jeremy's advice about visiting a pearl farm in China up above applies to you too. And Pattye's advice to go to Guaymas and visit Cortez Pearls is excellent. You will never see anything like the Cortez pearl operation in China. It is the pearl farm one dreams of visiting. Tahiti has some, too, like Kamoka Pearls