1) The picture has to be hosted some where online. Facebook, Google Photo, the Photos section here on Kingsnake, Snapfish, etc, are all places where you can upload the photos to be hosted.
2) You have the image tags mostly correct. The URL of the photo needs to be in between the tags. Also, the end tag (the one on the right) needs to have a backslash, [/img], in it to indicate the end of the code.
For example (remove the " marks):
["img"]http://www.desertusa.com/magfeb98/kingsnake.jpg["/img"]
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25 year old 0.1 from Lincoln, NE
Ball Pythons - 0.1 Pastel, 1.0 Pastel het Pied, 0.1 Pied, 0.1 Cinn, 1.0 Black Pewter, 1.0 Woma (hidden gene?), 0.1 Yellowbelly, 2.1 Normals
Kingsnakes - 1.0 L. m. thayeri, 0.1 L. m. thayeri X L. alterna, 1.0 L. g. californiae
Other - 0.1 Whitesided P. catenifer sayi, 1.0 H. nascicus, ?.? Chrysemys picta, 0.1 crazy cat, 1.0 husband