Ok what you do is go to the Photo Gallery link at the top of this page, then just follow the instructions there on how to upload a photo. You need to make the photo small because it won't take them if they're too large. Even though they come out really small once you get them uploaded they don't look small anymore.
Now after you have them uploaded into the gallery and you come back to the board to post the photo, it's easy because once you open up a new message if you'll scroll down you'll see that the links to your photos are already here in the window you're using to post a new message. All you have to do is highlight the photo you want to post here & then click post message.
A lot of times I will click on preview message first so that I can be sure I have the correct photo, if I do I hit post message & bada bing bada boom.. my photo is here. 
I'll highlight one now.. here's Dolly having a cookie

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PHRatz