You have to upload them to photobucket or another photo hosting website.
Then post the IMG Code into your post.
So the code will look like this, [IMG]http://img.photobucket.com/albums/v93/aznw1f/dog/887180_4619102709447_563979686_o_zpsf615f2a7.jpg[/ IMG]
And come out like this on the forum:
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